No matter what, it will cost 174.20 per month for insurance and payment. Whether you drive the car 1 mile, or 1000 miles, you will pay 174.20 per month for this. That makes 174.20 your "constant" figure. Miles driven can vary month to month, so this will be your variable figure (or calculated amount).
We know that "x" represents miles, and it costs .29 "per mile". So we know that part will be .29x ( 29 cents multiplied by who knows how many miles). And because we know we're going to pay 174.20 every month no matter what, we add this to whatever our costs per mile total is ( this makes it our + b ).
So the answer would be y = .29x + 174.20
4/17/2013

Nickolaus M.