If the sum of two numbers is 50 and their difference is 10, find the two numbers.
Correct: C
Let the two numbers be x and y. We are given that x + y = 50 and x - y = 10. Adding these two equations, we get 2x = 60, which implies x = 30. Substituting x = 30 in the first equation, we get 30 + y = 50, which implies y = 20. Therefore, the two numbers are 30 and 20.