What is 20/15 simplified? 

20/15 is an imporoper fraction which means that numerator is larger than the denominator

It can be further simplified

fractions can be simplified by finding the highest common factor for both 15 and 20 and dividing the numerator by the highest common factor

factors for 15 and 20 are as follows

15 - 1,3,5,15

20,-,1,2,4,5,10,20

the greatest common factor is 5

so divide both by 5

this can be written as a proper fraction

in 4/3 there's one whole number and 1/3 remaining

so anwer is