Question

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

Answer 1

Answer:

y = 21

Step-by-step 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.

$\frac{6}{7} = \frac{18}{y}$

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

$\frac{6}{7} = \frac{18}{y}\\y*\frac{6}{7} = \frac{18}{y}*y\\\frac{6}{7}y = 18\\\frac{6}{7}y / \frac{6}{7} = 18 / \frac{6}{7}\\y = 21$

y is 21 when x is 18.