math word solving

Question

At a furniture manufacturer, worker A can assemble a shelving unit in 5 hours. Worker B can assemble the same shelving unit in 3 hours. Which equation can be used to find t, the time it takes for worker A and worker B to assemble a shelving unit together?

worker A 1\5 worker B 1\3

Answer 1

Both working together can assemble 1/5 +  1/3 of the shelving unit each hour.

1/5+1/3=8/15 of the unit is assembled by them working together each hour

How long will it take to assemble the unit if 1/15 of the unit is assembled each 1/8 of an hour?

1 unit or 15/15 of a unit is assembled in 15/8 hours.