Question

Suppose that y varies directly with x and y = 3 when x = 9. What is y when x = 18?

Answer 1

y = 6

Explanation:

Use the direct variation equation, y = kx

Plug in y = 3 and x = 9, and solve for k

y = kx

3 = k(9)

1/3 = k

So, the equation is y = 1/3x

Plug in 18 as x and solve for y

y = 1/3x

y = 1/3(18)

y = 6

So, when x = 18, y = 6