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

### Instruction:
Matias is a salesman in a bookstore. He sold 7 books on Tuesday and three times as many on Wednesday. If the sales from Wednesday were tripled on Thursday, how many books did Matias sell during these three days combined?

### Response:
 Jumanne, Matias aliuza vitabu 7.
Jumatano, Matias aliuza 3*7 = <<3*7=21>>21 vitabu.
Alhamisi, Matias aliuza 3*21 = <<3*21=63>>63 vitabu.
Matias aliuza 7+21+63 = <<7+21+63=91>>91 vitabu katika siku hizo tatu.