# math

x varies directly with y and z
x=1200,when y=20 and z=30. Find x when y=10 and z=20

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1. x(y,z) = kyz
1200 = k*20*30
k = 2
so,
x(y,z) = 2yz
x(10,20) = 2*10*20 = 400

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