1. if y is inversely proportional to x, and y = 36 when x = 5, then find y when x = 3?

2. if y varies inversely as x, and y = 27 when x = 12, find x when y = 18?

3. if z varies jointly as x and the square of y, and z = 20 when x= 4 and y = 2, find z when x = 2 and y = 4?

4. if z varies directly as the square of x and inversely as y, and z = 20when x = 2 and y = 4, find z when x = 4 and y = 2?