Cooper works part time for a moving company. One day he had to move 34 boxes from a truck to inside a house. After moving some boxes, he took a break and told his boss that he has only 15 boxes to move. Which equation below can be solved to find how many boxes Cooper moved before his break. A. 15+34=x B. 15−x=34 C. 34−x=15 D. 34+x=15