Question

alan would take 5 hours to build the wall of a house, and gavin would take 7 hours to build it alone. when they work together, they talk a lot, and their combined output decreases by 26 bricks per hour. working together, they build the wall in 4 hours. how many bricks are in the wall?

Answer 1

96 bricks

Explanation:

Alan does 1/5 of the job in an hour. Gavin does 1/7 of the job in an hour

Together, 12/35 of the job should be done in an hour. In
`2 (11)/(12)` hours, the work should be done.

rate at 4 hours=
`2 (11)/(12)`*(normal speed-26)

To clarify, x=the normal rate

4 hours(normal rate-26)=
`2 (11)/(12)`(normal rate)

4(x-26)=
`2 (11)/(12)`x

x=96