Looking for a better explanation

At a loading doc, each worker on teh night crew loaded 3/4 as many boxes as each worker on the day crew. If the night crew has 4/5 as many workers as the day crew, what fraction of all the boxes loaded by teh two crews did the day crew load?
A 1/2
B 2/5
C 3/5
D 4/5
E 5/8

E

Thanks!