Asked by Anonymous

x varies directly with y and z
x=1200,when y=20 and z=30. Find x when y=10 and z=20
Answered by Steve
x(y,z) = kyz
1200 = k*20*30
k = 2
so,
x(y,z) = 2yz
x(10,20) = 2*10*20 = 400