Question

a plumber finds that Andy can complete a certain job in 9 hours and Frank can complete the same job in 6 hours. how long would it take them to complete the job if they worked together?
A. 5 hours
B. 3.6 hours
C. 15 hours
D. 7.5 hours​

Answer 1

Answer:

3.6 hours is your answer

Answer 2

Step-by-step explanation:

joint speed = 1/ 9 + 1/6 = 15/54

time = 54/15 = 3 hours and 10 minutes