1. Solving Application Problems Using System of Equations Section 4.3

2. Problem solving procedure 1. Select a variable to represent each unknown. 2. Write a system of equations. (# of equations is the # of variables) 3. Solve the system. 4. Answer the question (include units if applicable)

3. Examples, from p 231 #12 A store has a clearance sale so that all t- shirts sell for $12 and all shorts sell for $15. the day the sale began, 57 clearance items sold (t-shirts and shorts) for a total of $747. How many t-shirts and how many shorts were sold?

4. #29 A boat travels 36 miles upstream in 3 hours. Going downstream, it can travel 48 miles in the same amount of time. Find the speed of the current and the speed of the boat in still water. #32 If a plane can travel 320 miles per hour with the wind and only 280 mph against the wind, find the speed of the wind and the speed of the plane in still air.

5. #33 How many milliliters of a 55 HCl mixture and a 20% HCl mixture must be combined to get 10 milliliters of 12.5% HCl mixture? #34 How much of a 45% saline solution and a 30% solution must be mixed to produce 20 liters of a 39% solution?