Enrico spent 0.4 hour completing his math homework. Then he spent 7 over 20 hour completing his science homework. What is the total number of hours Enrico spent on his math and science homework?

Answer 1

0.4 + 7/20 = 0.4 + 0.35 = 0.75
or
2/5 + 7/20 = 8/20 + 7/20 = 15/20 = 3/4