F(x)=-0.6x2 g(x)=-1.2x2 1≤x≤5

The variable z is directly proportional to x, and inversely proportional to y. when x is 4 and y is 13, z has the value 1.2307692307692. what is the value of z when x= 9, and y= 20

Just tell me how to set up the equation.

If i have 20$ and i gave 5$ away how much i got