>Several people answered 40
>I can get 52 or 96, but not 40.
>What am I missing?


It's easy, Bill

On each row, the number on the right = the sum of two numbers on the left added to the number on the right above

So,

2nd row : 2 + 5 + 5 = 12
3rd row: 3 + 6 + 12 = 21
4th row: 8 + 11 + 21 = 40