First of all, the denominators are not the same. To fix this, simply multiply the two denominators together.
Now we have x/48 - y/48 = ?
How many times does 8 go into 48? 6 times. 6 times the numerator which is 7
How many times does 6 go into 58? 8 times. 8 times the numerator which is 1
Now we have 42/48 - 8/48 = 34/48
Can we simplify 34/48? Yes.
34/48 / 2/2 = 17/24
