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

### Instruction:
 Oscar anataka kufanya mazoezi kwa ajili ya mbio za marathon. Anapanga kuongeza maili 2/3 kila wiki hadi afikie mbio za maili 20. Anapaswa kuanza mazoezi wiki ngapi kabla ya marathon ikiwa tayari amekimbia maili 2?


### Response:
 Oscar anahitaji kuongeza muda wake wa kukimbia kutoka maili 20 - 2 = <<20-2=18>>18.
Oscar atahitaji jumla ya wiki 18 / ( 2 / 3 ) = <<18/(2/3)=27>>27 kujiandaa.