The variable of z

Question

The variable z is directly proportional to x, and inversely proportional to Y. When x is 9 and Y is 13, z has the value of 4.1538461538462. What is the value of z when x=16 and Y=21

round to at least the thousandths place if needed.

Answer 1

z = kx/y

k = 6

So the function is z = 6*x/y

Finally 6*16/21 = 96/21 = 4 and 12/21 = 4 and 4/7