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

### Instruction:
Bert bought some unique stamps for his collection. Before the purchase, he had only half the stamps he bought. If he bought 300 stamps, how many stamps does Bert have in total after the purchase?

### Response:
 ก่อนการซื้อ เบิร์ตมีแสตมป์ 300 * 0.5 = <<300*0.5=150>>150 ดวง
ดังนั้นหลังการซื้อ เขาจะมีแสตมป์ 300 + 150 = <<300+150=450>>450 ดวง