Question

A crew will arrive in one week and begin filming a city for a movie. The mayor is desperate to clean the city streets before filming begins. Two teams are​ available, one that requires 200 hours and one that requires "400" hours. If the teams work​ together, how long will it take to clean all of the​ streets? Is this enough time before the cameras begin​ rolling?

Answer 1

See below in bold.

Explanation:

You work in fractions of the city streets done per hour:

1/200 + 1/400 = 1 /x where x is the number of hours taken by 2 teams.

Multiply through by the LCM 400x:

2x + x = 400

3x = 400

x = 133.33 hours.

As there are 168 hours in a week they will have enough time.