1. Store A charges $3 per square foot for a wall-to-wall carpet and charges $85 for installation. Store B charges $2 per square foot for the same carpet and charges $100 for installation. Use a graph to determine the square footage for which the total cost of the carpet and installation at each store is the same.

2. A bag contains quarters and dimes. There are 15 coins in the bag. The value of the coins is $2.70. Use substitution to determine the number of quarters and dimes in the bag.

3. A telephone company offers two long distance plans. One plan charges $4.95 per mont and $.07 per minute. The other plan does not have a monthly fee and charges $.10 per minutes. Use linear combinations to determine the number of minutes for which the cost of each plan is the same.

4. Twice Matt's age minus Ian's age is equal to 9. Twice Ian's age minus 8 is equal to twice Matt's age. Use linear combinations to determine Matt's age and Ian's age.

5. You want to sell your old stereo system. You place an advertisement about your stereo system in the classified section of your local newspaper. The selling price listed in the advertisement is $80.50. You decide to decrease the price by 10% each week that you do not sell the stereo system.

a. Write an exponential decay model to represent the situation.

b. You sell your stereo system for the price listed in the advertisement for the third week. How much money did you get for your stereo system?

6. It takes 12 bales of hay to feed two horses and 1 mule for one week. It takes 19 bales of hay to feed 3 horses and 2 mules for one week. How many bales of hay does it take to feed one horse for one week?

7. c + d = 10

c - d = 8

Find the value of c^2 -d^2 two different ways.

8. 2a + 3b =3

3a - b = 17

Find the absolute value of ab.

9. 2x +3y = 29

x + z =9

If z is 2 less than y, find x, y, and z.