Solve the system: x + y = 7 and 2x - y = 1.

• A. x = 7/3, y = 4/3
• B. x = 8/3, y = 13/3
• C. x = 5/3, y = 2
• D. x = 3, y = 4

Answer: (B)

Adding the two equations lets the y terms cancel, because +y and −y sum to zero. This leaves 3x = 8, so x = 8/3. Then plug that back into the first equation: 8/3 + y = 7, giving y = 7 − 8/3 = 13/3. Checking in the second equation: 2x − y = 2*(8/3) − 13/3 = 16/3 − 13/3 = 1, which matches. So the solution is x = 8/3 and y = 13/3.