Try another version of this question Suppose that `z` varies jointly with `x` and `y` . Find the constant of proportionality `k` if `z = 780` when `y = 8` and `x = 15` . Using the `k` from above write the variation equation in terms of `x` and `y` . Using the `k` from above find `z` given that `y = 13` and `x = 20` .
`k =`
`z =`
`z =`
If needed, round answer to 3 decimal places.
Enter DNE for Does Not Exist, oo for Infinity 6.5
`6.5 xy`
1690