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

### Instruction:
 Kulikuwa na washindani 50 katika mbio za baiskeli za hisani mwanzoni mwa mbio. Baada ya dakika 20, washindani wengine 30 walijiunga na mbio hizo. Idadi ya washindani iliongezeka mara mbili baada ya dakika nyingine 30. Ikiwa mwishoni mwa mbio ni watu 130 tu waliofika mwisho wa mbio, idadi jumla ya watu walioacha kabla ya kumaliza mbio ni ngapi?


### Response:
 Baada ya dakika 20, kulikuwa na washindani 50+30 = <<50+30=80>>80.
Baada ya dakika nyingine 30, idadi ya washindani iliongezeka mara mbili, jumla ya washindani ni 80*2 = <<80*2=160>>160.
Ikiwa idadi ya washindani waliofika mwisho ni 130, basi washindani 160-130 = <<160-130=30>>30 waliacha kabla ya kumaliza mbio.