Question

A standard bathtub holds 70 gallons of water. On average, it takes 7 and 1/2 minutes to drain a bathtub. How many gallons of water go down the drain each minute?

Answer 1

$\bf \begin{array}{ccll} \stackrel{drain}{minutes}&\stackrel{bathtub}{gallons}\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 7\frac{1}{2}&70\\ 1&x \end{array}\implies \cfrac{7\frac{1}{2}}{1}=\cfrac{70}{x}\implies \cfrac{\frac{15}{2}}{\frac{1}{1}}=\cfrac{70}{x} \\\\\\ \cfrac{15}{2}\cdot \cfrac{1}{1}=\cfrac{70}{x}\implies \cfrac{15}{2}=\cfrac{70}{x}\implies x=\cfrac{2\cdot 70}{15}$