I am getting 72/28 which cannot be right for this problem:
3/8h+7/12= 3/4
As in a similar question, I believe it may be better presented as:
3h/8 + 7/12 = 3/4
So, adding and sutracting fractions calls for finding a ..... common denominator. You will use the .... LCM, or Least common multiple.
The LCM for 8, 12, and 4 is ... 24. The fractions now become:
9h/24 + 14/24 = 18/24
multiply everything by 24:
9h + 14 = 18
subtract 14 from each side
9h = 4
h = 4/9
I hope this helps.
9/6/2013

Rusty P.