Let the two numbers be X and Y.
X/Y = 7/4
X - Y = 24
Rearrange the first equation to get X = 7Y/4. Then substitute this into the second equation to get
X - Y = 24
7Y/4 - Y = 24
3Y/4 = 24
3Y = 96
Y = 32
Then find X by plugging Y = 32 into the second equation:
X - Y = 24
X - 32 = 24
X = 56