Question

If y varies directly as x and y = 144 when x = 12, what is the value of y when x = 17?

Answer 1

$y=kx \\ \\ y=144 \hbox{ when } x=12 \\ \Downarrow \\ 144=k \times 12 \\ k=12 \\ \\ y=12x \hbox{ and } x=17 \\ \Downarrow \\ y=12 \times 17 \\ y=204 \\ \\ \boxed{y=204} \hbox{ when } x=17$