Question

If x varies directly with y and x = 10 when y = 15, find x when y = 12.

8

7.5

12

12.5

Answer 1

Varying directly uses the equation
\[\large x=ky\]


If y = 15 when x = 10....we plug those in...and solve for 'k'

'k' is our constant of variation (also known as a number we must multiply all 'y' by to reach the corresponding 'x'

So here...
\[\large 10=15k \]


solving for 'k' we get...?