Answer to Question #260386 in Algebra for Karuma

Question

A painting crew can paint a structure in 12 hr or in 7.2 Jr when working with a second crew. How long would it take the second crew to do the job if working alone

Answer 1

It fololws that a first painting crew can paint $\frac{1}{12}$ part of a structure in 1 hr, and they both can paint $\frac{1}{7.2}=\frac{5}{36}$ part of a structure in 1 hr. Therefore, the second crew can paint $\frac{5}{36}-\frac{1}{12}=\frac{5-3}{36}=\frac{2}{36}=\frac{1}{18}$ part of a structure in 1 hr. Therefore, the second crew do the job if working alone 18 hours.