Times the numerator and denominator so the two fractions are both the same
For example:
What is
3/4 - 1/3
Lowest common multiple of 3 and 4 is 12 so
To make 12 you times by 3 so..
4x3=12
Because you times the denominator you have to also times the numerator by the same number so
3x3=9
This means that 3/4 is equal to 9/12.
You then have to do the same thing for 1/3
To make 12 you times by 4 so..
3x4= 12
1x4=4
Therefore 1/3 is equal to 4/12
Now you can subtract them so the question was what is 3/4 - 1/3 and we know that it is also equal to 9/12 - 4/12
Therefore the answer is 5/12