Question

Use substitution to solve this system of equations. 4x-5y=19 y=8x-11

Answer 1

$4x-5y=19 \\ y=8x-11 \\ \\ \hbox{substitute 8x-11 for y in the 1st equation and solve for x:} \\ 4x-5(8x-11)=19 \\ 4x-40x+55=19 \\ 4x-40x=19-55 \\ -36x=-36 \\ x=\frac{-36}{-36} \\ x=1 \\ \\ \hbox{substitute 1 for x in one of the equations and solve for y:} \\ y=8 \times 1-11 \\ y=8-11 \\ y=-3 \\ \\ (x,y)=(1,-3)$