## Introductory Algebra for College Students (7th Edition)

$$x = 3$$
The coefficients of the $y$ term differ only in sign, so if we add these equations without modification, we will cancel out the $y$ term and can then solve for $x$: Let us add the equations. First, we cancel out the $y$ term: $x + 3y = 6$ $x - 3y = 6$ _____________ $2x = 6$ $2x = 6$ Now we add both sides of the two equations to get: $$4x = 12$$ Divide by $4$ to solve for $x$: $$x = 3$$