Help me EP!!

$\sqrt{x}*y=k$

$5*15=k$

$k=75$

$\sqrt{x}=\frac{75}{3}$

$x=625$

JP

y = k / (sqrtx)       sub in the values to calculate the proportionality constant  'k'

15 = k/(sqrt25)

k =75

3 = 75/(sqrtx)

75/3 = sqrt x

625 = x

thanks!