# algebra

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y varies directly with x. When y = 20, x = 50. Find x when y = 36.

• algebra -

y varies directly with x ----> y = kx , where k is a constant

20 = k(50
k = 2/5

y = (2/5)x
when y = 36
36 = (2/5)x
2x = 180
x = 90

or ... use a proportion

x/50 = 36/20
x = 50(36)/20 = 90

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