it takes joh 2 hours to finish working in a yard, mark can work on the same yard for 3 hours. how long will it take both of them if they work as a team?

Answer 1

If it takes them x hours working together, then

1/2 + 1/3 = 1/x

The equation reflects the idea of how much of the job each can do in an hour. Add that up, and it shows how much of the whole job gets done in an hour.

Answer 2

joh = 1 y / 2 h
m = 1 y / 3h
so
(1/2 + 1/3) yard per hour together = 5/6 y/h
(5/6) yards/hr * t hr = 1 yard
t = 6/5 hours