Question

The value of y varies directly with x, and y = 12 when x = −6.

Find y when x = −4.

Answer 1

Okay, so it varies directly. That means we can put it in a ratio.

Y = 12 when X = -6
Divide Y by X

Y/X = 12/-6
Y/X = -2

So now, we have an equation we can use, with the same ratio. Plug in -4 to X

Y/-4 = -2
Multiply both sides by -4
Y = -2*-4
Y = 8