Y=6x, 2x+3y=-20 Substitution means just plugging in another equation equal to a single variable in order to solve for the other variable, and then the first. In this case, the equation being plugged in is y=6x, so 6x will be put in place of y in the equation 2x+3y=-20. 2x+3(6x)=-20 2x+18x=-20 20x=-20 x=-1 And then x=-1 can be plugged into the original equation to find y. (And, if you wish, into the y= equation to check it.) 2(-1)+3y=-20 -2+3y=-20 3y=-20+2 3y=-18 y=-6 And to check it, we plug the two into the original y= equation. y=6x -6=6(-1) -6=-6 They are equal, so both check out. x=-1, y=-6
