Answer :
The equation describing variation will be found as follows:
zαxy
z=kxy
where k is the proportionality constant
k=z/xy
when x=3, y=-5 then z=-75
k=-75/(-5*3)=5
hence the formula will be:
z=5xy
zαxy
z=kxy
where k is the proportionality constant
k=z/xy
when x=3, y=-5 then z=-75
k=-75/(-5*3)=5
hence the formula will be:
z=5xy