Y directly proportional to WX and inversely to Z.
Y=k(WX)/Z
Where k is the constant of proportionality.
So, the first thing is to find the value of this constant.
k = YZ/WX
= (32×3)/(6×20)
= 96/120
= 0.8
The equation that models the relationship will be;
Y = 0.8(WX/Z)