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

• A. x = 3, y = 4
• B. x = 5, y = 2
• C. x = 2, y = 5
• D. x = 4, y = 3

Answer: (D)

Solving two linear equations by elimination lets you isolate one variable at a time. Add the equations: (x + y) + (x − y) = 7 + 1, which gives 2x = 8, so x = 4. Substitute back into x + y = 7: 4 + y = 7, so y = 3. Double-check: 4 − 3 = 1 and 4 + 3 = 7, which both hold. The solution is x = 4 and y = 3.