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

### Instruction:
 唐尼周一存了15美元，周二存了28美元，周三存了13美元。周四他花掉了到目前为止存款的一半。他花了多少钱？


### Response:
 唐尼在三天内总共存了$15+$28+$13 = $<<15+28+13=56>>56
他花掉了一半的存款，即$56*(1/2) = $<<56*1/2=28>>28