Submit a question to our community and get an answer from real people.

How do you get rid of the fractions if the denominators are different?

for example 1/10+2/8=something

Report as

In order to get rid of the denominator, you must get the denominator to be the same number.... EX:
1/10 + 2/8=?
10 and 8 both go in to 40. In order to get the denominator of ten to 40, you must multiply the whole fraction by 4/4
1 4 4
- * - = -
10 4 40
Do the same thing for 8.... In order to get 8 to 40, you must multiply the whole fraction by 5/5
2/8 x 5/5 = 10/40 (It took forever to lay it out like the one above lol)
Now you can add the fractions...
4/40 + 10/40 = (10+4)/40
14/40
(or 7/20 if you simplify the fraction)
If you are confused by anything I said, just let me know your ? and ill try and help you as best as I can

Report as
but can you multiply the two fraction by different things? because from my little bit of algebra 1 knowledge i don't think u can
Report as
Haha this is one of those weird exceptions... When working with fractions, you are "allowed" to multiply them by two different things. Not sure how or why lol
Report as
If you wanted to, you could make the denominator in these fractions 80 instead, and multiply the 1/10 x 8/8 (8/80)
and the 2/8 x 10/10 (20/80) and when you simplify the fractions, you will get the same answer
Report as
but what if there is an answer to the equation there, i just didnt tell u it cus i forgot...do i have to multiply that by anything?
Report as
and are you SURE your right?!
Report as
If you had the answer we got from this equation (7/20) = to something, then we could either use a proportion to solve (cross multiply), or else there would be nothing to solve in this problem. For example...
7/20=s/2
Cross multiply: (7)x(2)= (20)x(s)
14= 20s
14/20=s (7/10)

If you had 7/20=4/15, then that wouldn't be a solve-able equation...
Report as
You can use different numbers for different fractions because you're not changing the value of anything. 1/2 and 4/8 are the same. As long as whatever is done to the denominator is done to the numerator, it's fine.
Report as
And Im 100% sure :)
Report as
No you dont understand my question. Im supposed to JUST get rid of the fractions in the equations so that i can solve it normally.
Report as
Do you have the whole problem?
Report as
no. it WAS on a test but i need to know if i got it right becuase i wont know for a while
Report as
Report as
how do i get rid of the fractions to solve the equation for example-
1/3x+2/3y=6
so you would do...
3(1/3x+2/3y)=6
and you would get...
1x+2y=6
Bam. Done.
But my denominators are different so i need to know what to do
Report as
its is...
1/10x+2/8y=???
Report as
Ahhhhh......
In the quiz problem, you can multiply the whole thing by 40...
40(1/10x+2/8y)=___
40/10x+80/8y=___
4x+10y=___
Help at all?
Report as
y 40?
Report as
Because 8 and ten go into 40 (its the least common denominator). Try multiplying the fractions by like 2...
2(1/10x+2/8y)=???
It would do us no good, because those would simplify to 1/5 and 1/2...
By multiplying by the least common denominator, it gets rid of the denominator in both fractions
Report as
You can multiply and divide fractions with different denominators (for dividing, you multiply by its recpricol. For example, 2/8 divided by 3/8 is the same as 2/8 times 8/3. Then you just multiply across. 2/8 times 8/3 is 16/24 or 2/3.)

But you cannot do that when adding or subtracting fractions. You have to find the least common denominator first before adding or subtracting. So for example 3/8 + 3/4 would be 3/8 + 6/8 or 9/8 or 1 1/8.
Report as

Find a common denominator. For example, both 10 and 8 go into 40. So, to get 10 to 40, you have to multiply by 4. Do the same to the top number. 1 times 4 is 4. The first fraction is 4/40.
Then, to get the other denominator, 8, to equal 40, you have to multiply 8 by 5. Then, do the same to the numerator. 2 times 5 is 10. The second fraction is 10/40.

The two fractions are 4/40 and 10/40.
4/40+10/40=14/40

That's not all, though. Now you must simplify.
14/40 becomes 7/20

Report as
And 100 % sure :)
Report as

LCD of 10 and 8 is 40
since 10 X 4 is 40 multiply 1 X 4 to get
4/40
since 8 X 5 is 40 multiply 2 X 5 to get
10/40
4/40 + 10/40 = 14/40 which is 7/20

Report as
are you SURE you can multiply the fractions by different things?! Because there is an answer to this equation its just not necessary to get rid of the fractions...right?! or no?
Report as
Yes, I am positive. Of course you could also use long division to get the decimal equivalent of each fraction and then add them together but that would take longer and involve more steps which increases the likely hood of error, but it would get you to the same answer. If you did it the way I showed you and then you used long division to convert the final fraction to a decimal number.
Report as
But you don't have to take my word for it. Watch this quick video maybe it will make it clear for you.
Report as
Let me know if this helps
Report as
it does thanks
Report as

you have to change both deominators to a number that they both go into evenly like your EX: 1/10= 5/40, and 2/8=10/40 (because both denominators can go into the number) and then add them.

Report as