Question

Y varies directly as x and y = 9 when x = 72

Answer 1

y =
`(x)/(8)`

Explanation:

since y varies directly as x, then the equation relating them is

y = kx ← k is the constant of variation

to find k use the given condition y = 9 when x = 72

k =
`(9)/(x)` =
`(9)/(72)` =
`(1)/(8)`, hence

y =
`(1)/(8)` × x =
`(x)/(8)`