Y varies jointly with w and x, inversely with z, and suppose y=360 when w = 8, x=15, and z = 3. Write the equation that models this relationship

Y varies jointly with w and x, inversely with z

this means that

y ∝ wx / z

in equation form

y = kwx / z

where k is the proportionality constant

360 = k (8) (15) / 3

k = (360) (3) / (8) (15)

k = 9

so the eqution is

y = 9wx / z