Final answer:
Joe has to make 43 additional trips to school, walking 1 kilometer each trip, in order to reach a total of 46 kilometers after already having walked 3 kilometers.
Step-by-step explanation:
To calculate how many trips Joe will have to make to walk a total of 46 kilometers, considering he has already walked 3 kilometers and plans to walk 1 kilometer per trip to school, we can use a simple arithmetic calculation. First, we subtract the distance Joe has already walked from the total desired distance: 46 km - 3 km = 43 km remaining to be walked. Then, we divide the remaining distance by the distance Joe plans to walk each trip to get the number of trips required: 43 km ÷ 1 km/trip = 43 trips. Therefore, Joe needs to make 43 additional trips to school.