z=4. If z varies inversely as w, and z=5 when w=8, then when w=10 the value of z is 4.
This exercise is an example of reverse proportionality, Two magnitudes a and b are inversely proportional when there is a constant k such that
a⋅b=k, where constant k is called the proportionality constant.
Then if z varies inversely as w, and z=5 when w=8
z.w=k -------> 5.8=k -------> k=40
So, let's find z when w = 10. With k = 40
z.w=K, clear z from the equation
z=k/w -------> z=40/10 -----> z=4
