7x -4y = 9
2x +y = 9
multiply the bottom equation by 4
7x -4y = 9
8x +4y = 36
add the equations
7x -4y = 9
8x +4y = 36
15x +0y = 45
simplify and solve for x
15x = 45
x = 3
pick one of the equations
2x +y = 9
enter the value for x
2(3) +y = 9
solve for y
6 +y = 9
y = 3
Answer: x = 3, y = 3
check:
7x -4y = 9
7(3) -4(3) = 9
21 -12 = 9 True
check
2x +y = 9
2(3) +3 = 9
6 + 3 = 9 True