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Suppose that z varies jointly with x and y.

Find the constant of proportionality k if z = 747 when y = 6 and x = 15.
k =
Using the k from above write the variation equation in terms of x and y.
z =
Using the k from above find z given that y = 12 and x = 18.
z =

If needed, round answer to 3 decimal places.
Enter DNE for Does Not Exist, oo for Infinity