Solving equations

Part 1

2x + y = 15
y = -x + 2
Solve y
  1. y = 2x - 15
    y = -x + 2
  2. 2x - 15 = -x + 2
  3. 3x - 15 = 2
  4. 3x = 17
  5. x = 17/3