Question

Suppose y varies directly as x, and y = 10 when x = 25. Find y when x = 18.

Answer 1

y = 7.2

Explanation:

Given that y varies directly as x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = 10 when x = 25, then

10 = 25k ( divide both sides by 25 )

`(10)/(25)` = 0.4 = k

y = 0.4x ← equation of variation

When x = 18, then

y = 0.4 × 18 = 7.2

Answer 2

I believe y would equal 3?