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?
It’s 2021 and Mark was born in 1976 so Mark is 2021-1976 = <<2021-1976=45>>45 years old
Graham is 3 years younger than Mark who is 45 so Graham is 45-3 = 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