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

### Instruction:
Ben starts each day with $50, spends $15 every day and saves the rest. After a few days, his mom doubled his total savings and his dad gave him an additional $10. If he now has $500, How many days have elapsed?

### 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