Combined Total Parking Fee Calculation

In a certain city, the parking fees for two types of vehicles, cars and motorcycles, are determined by a system of linear equations. The total monthly parking fee (in dollars) for a car is represented by the equation:

$$ C = 20x + 10 $$

where $C$ represents the total fee and $x$ is the number of parking days in a month, up to a maximum of 15 days. For motorcycles, the parking fee is represented by the equation:

$$ M = 15y + 5 $$

where $M$ represents the total fee for motorcycles and $y$ is also the number of parking days in a month, up to a maximum of 15 days.

A customer parks their car for 10 days and their motorcycle for 12 days. What will be the combined total parking fee for the month, expressed as a single fraction in simplest form?