Let x represent the smallest number. Consecutive numbers differ by 1. It means that the second number would be x + 1 and the largest number would be x + 1 + 1 = x + 2
We were told that seven times the smallest of three consecutive numbers is equal to five times the largest number. It means that
7x = 5(x + 2)
7x = 5x + 10
7x - 5x= 10
2x = 10
x = 10/2 = 5
The first number is 5
the second number is 5 + 1 = 6
The third number is 5 + 1 + 1 = 7