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

### Instruction:
Bella bought stamps at the post office. Some of the stamps had a snowflake design, some had a truck design, and some had a rose design. Bella bought 11 snowflake stamps. She bought 9 more truck stamps than snowflake stamps, and 13 fewer rose stamps than truck stamps. How many stamps did Bella buy in all?

### Response:
 จำนวนแสตมป์รถบรรทุกคือ 11 + 9 = <<11+9=20>>20 ดวง
จำนวนแสตมป์ดอกกุหลาบคือ 20 - 13 = <<20-13=7>>7 ดวง
เบลล่าซื้อแสตมป์ทั้งหมด 11 + 20 + 7 = <<11+20+7=38>>38 ดวง