If a car is towed 12 miles to the repair shop and the tow charge is 3.50 per mile how much does the tow cost

To answer this question, you just multiply the cost per mile times the number of miles.  This makes sense because if it costs 3.50 per mile, the cost for 12 miles should be 12 times that amount.

So, 3.5 × 12 = 42

The tow costs 42 dollars.