multiply each equation by the value that makes the coefficients of x opposite
(-2) x (x+3y) = (-2) (1)
2x + 4y = -2
simplify
-2x - 6y = -2
2x + 4y = -2
add the two equations together to remove x from the system
-2x - 6y = -2 + 2x + 4y = -2 = -2y = -4
divide each term by -2 and simplify
y=2
