Answer:
When x = 1 and z = 4,

Explanation:
The variation described in the problem can be written using a constant of proportionality "b" as:

The other piece of information is that when x = 5 and z = 1, then y gives 25/9. So we use this info to find the constant "b":

Knowing this constant, we can find the value of y when x=1 and z=4 as:
