Question

The elevator in the Empire State Building can pass 80 floors in 45 seconds. How many floors can it pass in 9 seconds?

Answer 1

$\bf \begin{array}{ccll} floors&seconds\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 80&45\\ f&9 \end{array}\implies \cfrac{80}{f}=\cfrac{45}{9}\implies \cfrac{80\cdot 9}{45}=f$