An electrician starts off the day with 600 feet of copper wiring on his truck. During the course of

An electrician starts off the day with 600 feet of copper wiring on his truck. During the course of the day he uses pieces 100, 82, 25, and 40 feet long. The next day, he purchases another 400 feet and puts it on his truck and later in the day uses pieces of 41, 39, and 44 feet long. How many feet of wiring are still on the truck at the end of the second day?

If the electrician uses pieces, we subtract. If he purchases pieces, we add. So we have:
600 - 100 - 82 - 25 - 40 + 400 - 41 - 39 - 44 = 629 feet