the sum of two numbers is 47, and their difference is 15. What is the larger number?
Let the two numbers be x and y.
x + y = 47
+
x - y = 15
__________
2x + 0y = 62 Adding both equations.
___________
2x = 62
x = 62/2
x = 31.
x is definitely the larger of the two numbers because x - y = 15
The larger number is 31.