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

### Instruction:
Tracy has a charity book collection store from which she receives book donations from members of her town. Any person who wants to borrow a book is free to do so as long as they return the book after they've finished reading. She has already received 300 book donations. If ten people come and donate five books each in a week, and a total of 140 books are borrowed by other people to read, calculate the total number of books she has remaining in the store?

### Response:
 Watu kumi wamechangia vitabu 10*5 = <<10*5=50>>50.
Jumla ya vitabu dukani baada ya michango mpya ni 350 vitabu.
Wakati baadhi ya vitabu vinakopwa, jumla ya vitabu anavyobaki navyo ni 350-140 = <<350-140=210>>210.