Example of subtracting fractions with unlike denominators | Fractions | Pre-Algebra | Khan Academy

If you conquered adding fractions with different denominators, then subtracting fractions will be a snap. Don't worry...we'll take it slow and explain every step.

Missed the previous lesson?

Pre-Algebra on Khan Academy: No way, this isn't your run of the mill arithmetic. This is Pre-algebra. You're about to play with the professionals. Think of pre-algebra as a runway. You're the airplane and algebra is your sunny vacation destination. Without the runway you're not going anywhere. Seriously, the foundation for all higher mathematics is laid with many of the concepts that we will introduce to you here: negative numbers, absolute value, factors, multiples, decimals, and fractions to name a few. So buckle up and move your seat into the upright position. We're about to take off!

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[itznaisa]

Math just needs to grow up and solve it's own problems

[omarabdel]

Does he write with the mouse or? If he writes with the mouse he is

[matt-trqh]

I'm grade 7 and I get this ayyaya I'm happy :P

[watersfamily]

Wow. He just saved me 4 hours of homework!

[geraldinegol-lod]

I think there is one pattern to answer it.. First you need to get the LCD( denominator of the first fraction x the denominator of the second fraction) which is 156 then divide it to the denominator of the first fraction which is 12(156 divided by 12) which is 13 then multiply it to the upper part of the fraction which is 7 and the answer is 91. To do it, do the same thing in the second fraction. Now we get the fraction of 91/156 - 72/156 and the answer is 19/156. HOPE YOU GET IT. Remember:
1st Get the LCD of the fraction
2nd LCD x numerator
3rd do it to the 2nd fraction
4th Subtract them now
5th Simplify if POSSIBLE.


Hope you understand
I am only a 6th grader.

[sammydeleon]

Thank you for helping me with my math I'm in 5 grade

[Oogwoy]

I don't get it where he got 72 but I love math

[shelly]

It really actually helped me, I am starting to finally get it.Thank you KHAN ACADEMY.

[Amias]

Thank you soo much you saved helped me a lot with my work :))

[randallmonette]

What if there is a common denominator?

[nebulousgamer]

thanks lol math test tomorrow 😥😅🙄 also watch at school im at Malc lol

[mcndonnybaby]

you are really good att math you helped me with my math

[jeanmarquez]

So it’s denominator times denominator??

[ABS]

So at the end if for example the 19 could fully go into the 156 without any remainders, what would the answer be? A whole number?

[sarahmikkelsen]

thank u so much i have homework do tomarrow and i totally forgot how to subtract fractions

[kaijanssen]

i just got this as an assignment for online school cuz CoROnA VirUS

i literally had to watch like almost more than 5 videos on fraction cuz i need to be more clear

[amirauwu]

Thx you helped so much i have a test tommorow and i knew nothing till i watched this im in grade 5