Question

a cable installer can make 42 installations in 6 hours how long will the installers been making a hundred and forty-seven installations

Answer 1

This problem can solve by the rule of three.
42 installations-----------------------6 hours
147 installations---------------------- x

x=(147 installations * 6 hour) / 42 installations=21 hours.

Answer: 21 hours.

Answer 2

147/42=3.5*6=21
21 hours is your answer