Ratio and Proportion. The bigger plus two times the smaller number is equal to 42

The ration between 2 numbers is $\displaystyle -\frac{3}{8}$. If the bigger numer plus two times the smaller number is equal to 42, find out the bigger number value.

$\displaystyle \frac{x}{y} = -\frac{3}{8}$

$\displaystyle -3y=8x$

$\displaystyle y = -\frac{8x}{3}$ $\displaystyle x = \frac{-3y}{8}$

How do I find out which one is the bigger? obviously 3 is smaller than 8, but, couldn't it be the number 3 positive and the number 8 negative, therefore number 3 could be bigger than 8?

Thanks for the help in advance.