Solve the system of equations: {x+y=5, x-y=7}

1. Add the two equations: (x+y) + (x-y) = 5 + 7, which simplifies to 2x = 12.

2. Solve for x: x = 12 / 2 = 6.

3. Substitute x=6 into the first equation: 6 + y = 5. Solve for y: y = 5 - 6 = -1.

Answer: x=6, y=-1