Answer: 200 miles
Explanation:
Given
Company A charges 
 per day and
 per day and 
 per mile extra
 per mile extra
While company B charges 
 per day and
 per day and 
 per mile extra
 per mile extra
Suppose a car run x miles in a day in both the cases
So, Cost for Car A=35+0.1x
Cost for car B=25+0.15x
when the price is equal
35+0.1x=25+0.15x
10=0.05x
x=200 miles