Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 伊莎贝拉和亚历克西斯去商场买裤子和连衣裙。亚历克西斯买的裤子和连衣裙是伊莎贝拉的3倍。如果亚历克西斯买了21条裤子和18件连衣裙，伊莎贝拉总共买了多少条裤子和连衣裙？


### Response:
 伊莎贝拉买的裤子数量是21 / 3 = <<21/3=7>>7条裤子。
伊莎贝拉买的连衣裙数量是18 / 3 = <<18/3=6>>6件连衣裙。
伊莎贝拉总共买了13条裤子和连衣裙。