In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?
I can find the answer easily enough by writing down all the numbers and back solving using the answers, but there has to be an easier way to attack this problem. Any ideas?
From the top, the board after the 19th board, i.e., the 20th board from the top is the 15th board from the bottom. Total boards = 19 + 15 = 34.