Read this scenario. Eve and her book club raised money by having a bake sale. They sold 37 cookies, 30...

Read this scenario.
Eve and her book club raised money by having a bake sale. They sold 37 cookies, 30 biscotti,
and 15 muffins on Monday, raising a total of $89.50. They raised $84 on Tuesday by selling
25 cookies, 28 biscotti, and 19 muffins. On the last day of the sale, they raised $93 by selling
30 cookies, 36 biscotti, and 18 muffins. How much did they charge for each type of pastry?
A system of three equations can be used to solve the problem. Here are two of the equations:
37x + 30y + 15z = 89.5
25x + 28y + 19z = 84
What is the third equation in the system?
15x + 19y + 18z = 93
30x + 36y + 18z = 93
84x + 25y + 28z = 19
93x + 30y + 36z = 18