Final answer:
Bobby can make 11 pieces of train cars from the given piece of wood.
Step-by-step explanation:
To find out how many train cars Bobby can make, we need to divide the length of the wood by the length required for each train car.
Since Bobby needs 3/4 inches of wood for each train car and he has a piece of wood that is 8 1/4 inches long, we can divide the length of the wood by the length per train car:
8 1/4 inches ÷ 3/4 inches = 11 pieces
Therefore, Bobby can make 11 pieces of train cars from the given piece of wood.