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

### Instruction:
Betty is 60 years old, and she is the oldest person in the family. Her daughter is 40 percent younger than she is, and her granddaughter is one-third her mother's age. How old is the granddaughter?

### Response:
 ลูกสาวของเบตตี้น้อยกว่าเธอ 40/100 * 60 = <<40/100*60=24>>24 ปี
นั่นหมายความว่าลูกสาวของเธออายุ 60 - 24 = <<60-24=36>>36 ปี
ดังนั้นหลานสาวอายุ 1/3 * 36 = <<1/3*36=12>>12 ปี