please HELP ME answer this

Question

For the statement, find the constant of variation and the variation equation.
y varies jointly as x and the cube of z;=112 when x=77 and z =2
Find the constant of variation k.

Answer 1

y = k·x·z³

 

y = 112 when x = 77 and z = 2:

 

112 = k·77·2³

112 = k·616

112/616 = 2/11 = k