Final answer:
Tristan needs to make 8 trips to carry 40 cords of wood in his pickup truck.
Step-by-step explanation:
To find the number of trips needed to carry 40 cords of wood in Tristan's pickup truck that can carry (5)/(8)-cord of firewood, we need to divide the total amount of wood by the capacity of the truck. The capacity of the truck is (5)/(8)-cord of firewood, which is equivalent to 40/8 = 5 cords. Therefore, the number of trips needed is 40/5 = 8 trips.