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

### 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:
 Mark ana umri wa miaka 45 kwa sababu 2021 - 1976 = <<2021-1976=45>>45.
Graham ana umri wa miaka 42 kwa sababu 45 - 3 = <<45-3=42>>42.
Janice ana umri wa miaka 21 kwa sababu 42 / 2 = <<42/2=21>>21.