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

### Instruction:
Donny saves $15 on Monday, $28 on Tuesday and $13 on Wednesday. On Thursday he spends half of his total savings so far. How much did he spend?

### Response:
 เงินออมทั้งหมด = 15 + 28 + 13 = <<15+28+13=56>>56
จำนวนเงินที่ใช้ = 56/2 = $<<56/2=28>>28