Question

Y varies directly affects if y equals negative five when x equals 15 find X when y equals three

Answer 1

Well,

We are given a direct proportion problem.

x varies directly as y.

$\frac{x}{y}$

When y = -5, x = 15.
$\frac{15}{-5} \ or\ \frac{3}{-1}$

Now, we are told to find x when y = 3.

$\frac{x}{3}$

We just have to recognize that the complete case is equal to the incomplete case.  In other words, we set the -3 equal to the x/3.

$\frac{3}{-1} = \frac{x}{3}$

Multiply both sides by the LCM.
LCM of -1 and 3 = 3

-9 = x

When y = 3, x = -9.