Solve the problem.
-A contractor finds that it takes Julie 9 hours to construct a wall of a certain size. It takes Leann 7 hours to construct the same wall. How long would it take if they worked together?
A) $\frac { 16 } { 63 }$ hours
B) 1 hour
C) $3 \frac { 15 } { 16 }$ hours
D) 16 hours

Question

Quizplus · Accepted Answer

Let x be the amount of time it takes for Julie and Leann to construct the wall together.
Then, we can set up the proportion: 
1/9 (Julie's rate) + 1/7 (Leann's rate) = 1/x (rate working together)
Multiplying both sides by the least common multiple of 9 and 7, which is 63, we get: 
7x + 9x = 63 
16x = 63 
x = 63/16 or 3 15/16 hours, which is Choice C.

Solve the Problem 1663\frac { 16 } { 63 }6316​ Hours B) 1 Hour C)

Solve the Problem $\frac { 16 } { 63 }$ Hours
B) 1 Hour
C)