In December of 2003, the average price for a gallon of regular gas in the United States was $\$1.50$.

1. At that time, what did it cost to buy $12$ gallons of gas?

   Hint(a):

   Multiply the cost by the number of gallons to determine what the cost would be.

2. Gerald paid $\$12.60$ for a tank of gas. How many gallons did he buy?

   Hint(b):

   This is the opposite of part (a). You know what the cost is, so divide the final price by the cost per gallon.

3. At right is a graph of this situation. Predict how the line would change to represent the average cost of gas in December of 2005, when gas cost $\$2.20$ per gallon on average.

   Answer(c):

   The line would get steeper.