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

### Instruction:
A school choir needs robes for each of its 30 singers. Currently, the school has only 12 robes so they decided to buy the rest. If each robe costs $2, how much will the school spend?

### Response:
 โรงเรียนต้องการซื้อชุดเพิ่มอีก 30 - 12 = <<30-12=18>>18 ชุด
ดังนั้นโรงเรียนจะต้องใช้เงิน 18 x $2 = $<<18*2=36>>36.