An equation in the system is y = x + 1. What is the other equation in the system if the solution is only at (0, 1)?
x − y = 1
2x + 2y = 4
x + y = 1
x + 2y = 2
x − y = 1
2x + 2y = 4
x + y = 1
x + 2y = 2