QUESTION: The sum of two numbers is 57 and the difference is 13. What are the numbers?
Let the two numbers be n1 and n2. Then,
n1 + n2 = 57
n1 - n2 = 13
add the two equations together.
2n2 = 70
n2 = 35
n1 = 57 - 35 = 22
Answer: the two numbers are 22 and 35