Question

Use substitution to solve 3x-2y=11 and x+2y=9

Answer 1

Solve the second equation for 2y.
.. 2y = 9 -x
Substitute that into the first equation.
.. 3x -(9 -x) = 11
.. 4x -9 = 11
.. 4x = 20
.. x = 5
Using our expression for 2y above,
.. 2y = 9 - 5
.. y = 4/2 = 2

The solution is (x, y) = (5, 2).