Can someone help with adding fractions?

Question

Ok so 1 5/20 + 2 16/20= 3 21/20(improper) so it equals 4 1/20 how did this happen? how is the answer 4 1/20? Did you divide? 20 into 21 or how did it change it from 4 to three?

Answer 1

1 5/20 + 2 16/20
rewrite the mixed numbers as improper fractions
=25 /20 + 56/20
Denominators are same, so, add the numerators
=(25+56)/20
=81/20
rewrite the improper fraction as mixed number
= 4 1/20