For systems of equations try using graphing, substitution, and elimination. For example {2x+7y=3} {x=-4y} You should first look at if you have a variable that can be substituted (using substitution) and in this case we do! you plug in the x into 2x meaning 2(-4y)+7y=3 1) distribute -8y+7y=3 2) combine like terms in this case -8y+7y= -1y 3) solve -1y=3 y=-3 so currently our solution is (0,-3) now we solve for x. we plug our solved variable (y) into 7y 7(-3) and our equation looks like this 2x+7(-3)=3 1) distribute 7(-3)=-21 2) rewrite then solve 2x+(-21)=3 3) isolate variable -21+21 & 3+21 4) 2x=24 5) solve 2/24 = 12 Meaning our solution is (12,-3) This is how to solve by substitution.