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

### Instruction:
Owen bred 21 turtles, and Johanna has 5 fewer turtles than Owen. After 1 month, Owen has twice as many turtles as before and Johanna loses half of her turtles and donates the rest to Owen. How many turtles did Owen have?

### Response:
 Johanna alikuwa na kasa 21 - 5 = <<21-5=16>>16.
Baada ya mwezi mmoja, Owen ana kasa 2 * 21 = <<2*21=42>>42.
Baada ya mwezi mmoja, Johanna ana kasa 1/2 * 16 = <<1/2*16=8>>8.
Baada ya mwezi mmoja, Owen ana kasa 42 + 8 = <<42+8=50>>50.