Question

Solve the equation with substitution 3x-2y=9 Y=2x-7

Answer 1

$3x-2y=9 \\ y=2x-7 \\ \\ \hbox{substitute 2x-7 for y in the 1st equation:} \\ 3x-2(2x-7)=9 \\ 3x-4x+14=9 \\ -x+14=9 \ \ \ |-14 \\ -x=-5 \ \ \ |\times (-1) \\ x=5 \\ \\ y=2x-7=2 \times 5-7=10-7=3 \\ \\ \boxed{(x,y)=(5,3)}$