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

### Instruction:
Brian can only hold his breath underwater for 10 seconds.  He wants to get better, so he starts practicing.  After a week, he's doubled the amount of time he can do it.  After another week, he's doubled it again from the previous week.  The final week, he's increased it by 50% from the previous week.  How long can Brian hold his breath for now?

### Response:
 Mwishoni mwa wiki ya kwanza, Brian sasa ameongeza mara mbili muda wake wa awali wa sekunde 10 hadi 10*2= <<10*2=20>>20 sekunde.
Mwishoni mwa wiki ya pili, Brian ameongeza mara mbili muda wa wiki iliyopita wa sekunde 20 hadi 20*2= <<20*2=40>>40 sekunde.
Mwishoni mwa wiki ya tatu, Brian anaongeza 50% ya sekunde 40 zaidi kwa muda wake, hivyo anaweza kushikilia pumzi yake kwa sekunde 40*.5= <<20=20>>20 zaidi.
Baada ya kuongeza sekunde 20 kwa muda wake kutoka wiki ya tatu, Brian sasa anaweza kushikilia pumzi yake kwa sekunde 40+20= <<20+40=60>>60.