1. Recall: In 1.5, we solved a system of equations by substituting one equation into the other Now, in 1.6, we will solve a system of equations by eliminating/removing a variable Everyday, Brenda bakes chocolate chip cookies and low- fat oatmeal cookies. She uses different amount of butter and oatmeal in each recipe. Brenda has 47 kg or butter and 140 kg of oatmeal Chocolate ChipLow-Fat Oatmeal 13 kg butter2 kg butter 8 kg oatmeal29 kg oatmeal

2. How many batches of each type of cookie can Brenda make using all the oatmeal and butter she has? Chocolate ChipLow-Fat Oatmeal 13 kg butter2 kg butter 8 kg oatmeal29 kg oatmeal Let r be the number of batches of chocolate chip cookies. Let s be the number of batches of low-fat cookies. 1. 13r + 2s = 47 2.8r + 29s = 140 Let’s multiply “1.” by 8 and multiply “2.” by 13 – this will allow us to eliminate the ‘r’ values: 1. x 8: 8(13r + 2s) = 8(47) 104r + 16s = 376 2. X 13: 13(8r + 29s) = 8(140) 104r + 377s = 1820

4. During a training exercise, a submarine travelled 20 km/h on the surface and 10 km/h underwater. The submarine travelled 200 km in 12 hours. How far did the submarine travel underwater?

5. Therefore, the submarine travelled 40 km underwater.