The sum of the numbers on two adjacent post- office boxes is 697. What are the numbers?

Question

The sum of the numbers on two adjacent post- office boxes is 697. What are the numbers? 

Answer 1

Let x = the number on one post-office box.  Since the second box is adjacent (next) to the first box, its number is x+1.

 

x + (x+1) = 697

 

2x + 1 = 697

 

Solve for x.