I get the whole trouble with fractions thing let me see if I can help!
so, 7/12 - 3/8 first you will always want to make the denominators even or the bottom #'s so to do that you have to find the GCD or greatest common denominator. Which would be 24. then you would have to do to the top what you did to the bottom by multiplying the top #'s by 2 for the first fraction (7/12) and then 3 for the denominator. now you just subtract the top numbers as if there wasn't even a fraction there. The bottom # doesn't change ever until you can simplify at the very end when you actually have an answer. so the answer would be 5/24 and that is as simplified as you can get it.
So basically when you are adding or subtracting fractions the denominators the number on the bottom of the fraction 12 in this case and 8 as well the two denominators sharing the least common multiple so what is the lowest multiple of 12 and 8 so count off 12: 12, 24, 36... 8: 8, 16 , 24 does that help?
