The cost of driving a car includes both fixed costs and mileage costs. Assume that insurance and car payments cost $\$ 350$ per month and gasoline, oil, and routine maintenance cost $\$ 0.29$ per mile.
(a) Find a linear function $f$ that gives the annual cost of driving this car $x$ miles.
(b) What does the $y$ -intercept on the graph of $f$ represent?