Rewrite 13/25 and 11/20 so they have a common denominator.

Answer 1

since 25 = 5*5 and 20=4*5
the LCD is 4*5*5 = 100
so, 13/25 = 13*4/100
11/20 = 11*5/100
...

Answer 2

13/25 and 11/20