Question

Mary takes 3 hours to mow the yard. It takes Sally 5 hours. How long would it take with them mowing it together? Give the exact decimal answer.
A. 3.4 hours
B. 2.725 hours
C. 1.875 hours
D. 2.225 hours

Answer 1

In one hour they both can do 1/x

1/3 + 1/5 = 1/x

8/15 = 1/x

x = 1.875 hours

Hope this helps!