Three consecutive integers have a sum of 81. find the integers.

Let n = your first number. 

If they are consecutive numbers, then n + 1 = your second number and n + 2 = your third number. 

It says "sum so we know to add them all together and solve for n. Solving for n then gives you the rest of your numbers. 

n + n + 1 + n + 2 = 81
3n + 3 = 81
3n = 81 - 3
3n = 78
n = 78 / 3
n = 26

n = 26
n + 1 = 27
n + 2 = 28

Your numbers are 26, 27, and 28.