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

### Instruction:
It’s February 2021.  Mark was born in January 1976.  Graham is 3 years younger than Mark, and Graham’s sister, Janice, is 1/2 the age of Graham.  How old is Janice?

### Response:
It’s 2021 and Mark was born in 1976 so Mark is 2021-1976 = <<45=45>>45 years old
Graham is 3 years younger than Mark who is 45 so Graham is 45-3 = <<45-3=42>>42 years old
Janice is 1/2 the age of Graham who is 42 so Janice is 42/2 = <<42/2=21>>21 years old
#### 21