Question

A goes through 2 3/5 boxes of nails in 3 1/2 rooves. How much would he use to finish 8 rooves?

Answer 1

By "rooves", do you mean "roofs", the plural of "roof"?

Answer 2

Use a proportion.

Let x = the unknown number of boxes needed for 8 roofs.

\(\large 2\dfrac{3}{5}\) boxes are to \(\large 3 \dfrac{1}{2}\) roofs as x boxes are to 8 roofs.

\(\Large \dfrac{2\frac{3}{5}}{3 \frac{1}{2}} = \dfrac{x}{8}\)

Convert the mixed numerals into fractions.
Then cross multiply and solve for x.