Since we don't know where to start, we can always give that a variable which in this case, it's X. Since we are finding the sum of three consecutive odd numbers, we will be skipping numbers so we can add 2 each time. Now, let's set up an equation.
X + X + 2 + X + 4 = 159
3x + 6 = 159
 -6 -6 ← subtract 6 on both sides
 3x = 153
 ÷3 ÷3 ← divide both sides by 3
 X = 51
 X + 2 = 53
 X + 4 = 55
Therefore, the smallest of our three consecutive integers is 51.