Since you didn't tell us if you are looking for the total length of all the wood Simon needs or if you are looking for how many pieces of wood he needs in total, I will tell you the answer to both.
If you want to find the total length of all the wood, multiply 217 by 15 since each piece is 217 feet long and there are 15 pieces he needs in total. The answer would then be 3255 feet of wood that Simon needs.
If you are looking for how many pieces of wood Simon needs in total, the answer is already in the question; 15 pieces.