Question

19 over 20 - 13 over 15

Answer 1

The answer is 1 over 12

Answer 2

19        13
-----  -  -----
 20       15

You have to find a common denominator (bottom number)
20 x 3 = 60 and 15 x 4 = 60

Then time the numerator (top number) by the same number you multiplied the bottom number by.
19 x 3 = 57 and 13 x 4 = 52

Now you can subtract the numerators while preserving the denominators.
57/60 - 52/60
= 5/60

Then, simplify.
1/12