Question

How do you solve the system `3x+2y=19` and `2x-3y=-9` by substitution?

Answer 1

`3x + 2y = 19 -> 3x = 19 - 2y -> x = (19 - 2y)/3`

`2x - 3y = -9 -> (2/3).(19 - 2y) - 3y = -9`

`38 - 4y - 9y = -27 -> -13y = -27 - 38 = - 65`

`y = 65/13` = 5

`x = (19 - 10)/3 = 9/3 = 3`

Check: 3(3) + 2(5) = 19. OK