Question

If y varies directly as x, and y=7 when x=6, find when y when x=18

Answer 1

y = 21

Explanation:

Lovely ratios can figure out what the missing side is.

You can either have x as the numerator or denominator, but keep it consistent, otherwise...wrong answer.

`(6)/(7) = (18)/(y)`

Now to figure out what y is, we need to isolate y.

`(6)/(7) = (18)/(y)\\y*(6)/(7) = (18)/(y)*y\\(6)/(7)y = 18\\(6)/(7)y / (6)/(7) = 18 / (6)/(7)\\y = 21`

y is 21 when x is 18.