Explanation

Since y varies jointly as x and z:

y = kxz

Given y = 33 when x = 9 and z = 12:

33 = k * 9 * 12

33 = 108k

k = 33/108

k = 11/36

Now, find y when x = 16 and z = 22:

y = (11/36) * 16 * 22

y = (11 * 16 * 22) / 36

y = 3872 / 36

y = 968 / 9