Xvaríes directly with y and z. x =1200 when y =20 and z=30 find x when y=10 and z=20

x = 400

Step-by-step explanation:

given that x varies directly with y and z the the equation relating them is

x = kyz ← k is the constant of variation

to find k use the given condition x = 1200 when y = 20 and z = 30

k = = = 2, thus

x = 2yz is the direct variation equation

when y = 10 and z = 20, then

x = 2 × 10 × 20 = 400