Solve.
-A painter can finish painting a house in 8 hours. Her assistant takes 10 hours to finish the same job. How long would it take for them to complete the job if they were working together?
A) $9 \mathrm { hr }$
B) $4 \frac { 4 } { 9 } \mathrm { hr }$
C) $7 \mathrm { hr }$
D) $\frac { 9 } { 40 } \mathrm { hr }$

Question

Quizplus · Accepted Answer

Working together, they can complete $\frac{1}{8} + \frac{1}{10} = \frac{5}{40} + \frac{4}{40} = \frac{9}{40}$ of the job per hour. To find the time taken to complete the job, take the reciprocal of $\frac{9}{40}$, which gives $\frac{40}{9}$ hours, or $4 \frac{4}{9}$ hours.

Solve -A Painter Can Finish Painting a House in 8 9hr9 \mathrm { hr }9hr

Solve
-A Painter Can Finish Painting a House in 8 $9 \mathrm { hr }$