## Algebra 1

Multiply the second equation by -1. Add the equations to eliminate y. $4x-7y=\ \ \ \ 3\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4x-7y=\ \ 3$ $\ \ x-7y=-15\ \ \ \$multiply by -1$\ \ \ \ \underline{\ -x+7y=15}$ $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 3x\ \ \ \ \ \ \ \ \ =18$ Solve for x. $3x=18$ $3x\div3=18\div3$ $x=6$ Substitute 6 for x in either equation and solve for y. $x-7y=-15$ $6-7y=-15$ $6-7y-6=-15-6$ $-7y=-21$ $-7y\div-7=-21\div-7$ $y=3$