Answer:

Explanation:
Given:

replacing the proportionality sign with a constant , we have :

substituting :
,
and
into the equation , we have :


divide through by 6

substituting
into the equation , the equation becomes

To find the value of z , when y = 4 , x = 80 , we will substitute the values into the formula , we have :


dividing through by 20 , we have :
