Question

you have a small business that shreds paper. dom can shred a truck load in 4 hrs. jim can do it in 2hrs.
if dom and jim work together then they should be able to finish the job in _________ hrs.

Answer 1

in 4/3 hours or 1 hr 20 min

Answer 2

how do you get it??

Answer 3

i think it is 1hrs and 20min

Answer 4

but how do you get it
explain the steps

Answer 5

dom can shred a truck load in 4 hrs. jim can do it in 2hrs.
See
since Dom can shred a whole truck in 4 hours, he can shred 1/4 in 1 hour
similarly
since Jim can shred a whole truck in 2 hours, he can shred 1/2 in 1 hour
So
together in 1 hour they can shred = 1/4 + 1/2 = 3/4
so to shred the whole truck together, they need 4/3 hours which is equal to 1hr20min