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

### Instruction:
Anna is reading a 31-chapter textbook, but she skips all the chapters that are divisible by 3. If it takes her 20 minutes to read each chapter, how many hours does she spend reading total?

### Response:
 Kuna sura 31 / 3 = <<31/3=10.333>>10 sura zinazoweza kugawanywa na 3.
Kuna sura 31 - sura 10 = <<31-10=21>>21 ambazo Anna anasoma.
Inamchukua dakika 20 * sura 21 = <<20*21=420>>420 dakika kusoma kitabu.
Kwa kuwa kuna dakika 60 katika saa, anatumia dakika 420 / dakika 60 = <<420/60=7>>7 masaa kusoma kitabu.