Well,
We are given a direct proportion problem.
x varies directly as y.
[tex] \frac{x}{y} [/tex]
When y = -5, x = 15.
[tex] \frac{15}{-5} \ or\ \frac{3}{-1} [/tex]
Now, we are told to find x when y = 3.
[tex] \frac{x}{3} [/tex]
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.
[tex] \frac{3}{-1} = \frac{x}{3} [/tex]
Multiply both sides by the LCM.
LCM of -1 and 3 = 3
-9 = x
When y = 3, x = -9.
