7. Using k as the constant of proportionality, write an equation that expresses: Z varies jointly as x and y. If Z = 24 when x = 3 and y = 4, find Z when x = 5 and y = 6. (show steps)

60

Step-by-step explanation:

"z varies jointly as x and y" can be expressed algebraically as z = kxy, where k is the constant of proportionality.

Given: z = 24 when x = 3 and y = 4, then 24 = k (3) (4), or 24 = 12k.

The const. of prop. must then be k = 2.

So now we have the specific relationship z = 2xy.

If x = 5 and y = 6, then z = 2 (5) (6) = 60.