Question

Working alone, ryan can dig a 10 ft. By 10 ft. Hole in five hours. Castel can dig the same hole in six hours. How long would it take them if they worked together?

Answer 1

This hole has an area of 100 ft².
This means Ryan does 20 ft² per hour
This also mean Castel does 16 2/3 ft² per hour.
20x + (16 2/3)x = 100
(36 2/3)x = 100
x = 30/11 hours (2.727272727272)