Question

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

Answer 1

Direct variation:
$y=kx$

y=144 when x=12.
$144=12k \\ k=\frac{144}{12} \\ k=12$

y=? when x=17.
$y=12 \times 17 \\ y=204$

y=204 when x=17.