1. Purpose: To Solve Word Problems using two variables instead of one. Homework: p. 424 1-15 ALL.

2. The sum of two numbers is 5. The larger number exceeds twice the smaller number by 14. Find the numbers. Let x = larger number AND Let y = smaller number x + y = 5 ***explains the 1 st equation x – 2y = 14 ****explains the 2 nd equation Use the SUBSTITUTION Method to Solve. x = 2y + 14 2y + 14 + y = 5 ***Solve for y. 3y = -9; y = -3; Plug in to find x. The numbers are 8 and -3.

3. A pet shop sold 23 puppies and kittens one week. They sold 9 more puppies than kittens. How many of each did they sell? Let p = puppies and k= kittens p + k = 23 AND 9 + k = p Substitute the 2 nd equation into the 1 st. 9 + k + k = 23 ***Solve for k. 2k = 14; k = 7 ****Solve for p. p + 7 = 23; p = 16 There were 16 puppies and 7 kittens sold.

4. A bank teller has 112 $5 bills and $10 bills for a total of $720. How many of each does the teller have? Let f = five and t = ten. f + t = 112 AND 5f + 10t = 720 t = 112 – f into the 2 nd equation. 5f + 10(112 – f) = 720 ***Solve for f. 5f + 1120 – 10f = 720 -5f = -400; f = 80 ***Solve for t. 80 + t = 112; t = 32 The teller has 80 $5 bills and 32 $10 bills.