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

### Instruction:
 卡拉在家庭聚会上发现自己比妈妈小20岁。她的妈妈比卡拉的祖母小15岁。如果卡拉的祖母是75岁，那么卡拉多大？


### Response:
 卡拉的妈妈：75-15=<<75-15=60>>60岁
卡拉：60-20=<<60-20=40>>40岁