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

### Instruction:
 Ben anaanza kila siku na $50, anatumia $15 kila siku na anahifadhi kiasi kilichobaki. Baada ya siku kadhaa, mama yake alizidisha akiba yake mara mbili na baba yake akampa $10 zaidi. Ikiwa sasa ana $500, ni siku ngapi zimepita?


### Response:
 Hebu tuchukue idadi ya siku kuwa x
Anahifadhi $50-$15=$<<50-15=35>>35 kila siku
Baada ya siku x, alikuwa amehifadhi $35*x=$35x
Mama yake alizidisha akiba yake kumpa $70x
Baba yake aliongeza $10 kumpa $500
Hivyo $70x=$500+$10
$70x=$500
x=$500/$70=<<7=7>>7 siku zimepita