Question

Alanna can detail a car in 45 minutes. Robbie can detail a car in 30 minutes. If they work together, how many minutes does it take them to detail a car?

A.) 15 minutes
B.) 18 minutes
C.) 75 minutes
D.) 90 minutes

Answer 1

The answer is B. 18 MINUTES

Answer 2

Amount of time needed by Alanna to detail a car = 45 minutes
Amount of time needed by Robbie to detail a car = 30 minutes
Then
The time needed by
Alanna and Robbie to detail a car together = (30 * 45)/(30 + 45) minutes
= 1350/75 minutes
= 18 minutes

From the above deduction, we can conclude that the correct option among all the options that are given in the question is the second option or option "B". I hope it helped you.