Question

Nine taps
fill a tank in 4hrs.
How many hours will 3 taps take

Answer 1

`\begin{array}{ccll} taps&hours\\ \cline{1-2} 9 & 4\\ 3& x \end{array} \implies \cfrac{9}{3}~~=~~\cfrac{4}{x}\implies 3=\cfrac{4}{x}\implies \stackrel{\textit{1 hour and 20 minutes}}{3x=4\implies x=\cfrac{4}{3}}`