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

### Instruction:
 Martin ana samaki wa dhahabu 18. Kila wiki samaki 5 hufa. Martin hununua samaki wapya 3 kila wiki. Martin atakuwa na samaki wangapi baada ya wiki 7?


### Response:
 Baada ya wiki 7, samaki 5*7 = 35 hufa.
Baada ya wiki 7, Martin hununua samaki 3*7 = <<3*7=21>>21.
Baada ya wiki 7, Martin atakuwa na samaki 18-35+21 = <<18-35+21=4>>4.