Three consecutive odd numbers add up to 129. What is the smallest of them?

Consecutive odd numbers are evenly spaced, so the middle one is the average: 129 ÷ 3 = 43. The three numbers are therefore 41, 43 and 45, and the smallest is 41. Answering 43 gives the middle number instead of the smallest, and 45 gives the largest. Check: 41 + 43 + 45 = 129.