get there rental car company charges 40 rental fee 15 gas and 025 mile driven

Get there rental car company charges a $40 rental fee, $15 for gas, and $0.25 per mile driven. For the same car, sunshine rentals charges $45 for rental and gas and $0.35 per mile. Find the number of miles for which the companies charges will be the same. Then find that charge. Explain why this equation works