OK
We have that
y = k wx / z and we know that y = 320 when w = 6, x = 20 and z = 3
So we need to find the proportionality constant, k......so we have.....
320 = k (6) (20) / 3
320 = k *120 / 3
320 = k * 40 divide both sides by 40
8 = k
So......the correct answer is
y = 8 wx / z
Here's the second one
xy + 16 = 0
https://www.desmos.com/calculator/r8slfagryd