SOLUTION: A local coffee shop sells 40 coffees and 20 pastries for a total of $130. The next day the same coffee shop sold 8 coffees and 5 pastries for $28.00. How much does a coffee and pas

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Question 1082298: A local coffee shop sells 40 coffees and 20 pastries for a total of $130. The next day the same coffee shop sold 8 coffees and 5 pastries for $28.00. How much does a coffee and pastry cost at the coffee shop? Write an equation that the coffee shop use to determine the total profit for any number of cups of coffee and pastries that they sell. Define your variables. Use your equation to calculate the profit from 72 coffees and 65 pastries.
Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
40c+20p = 130
8c+5p = 28 multiply all terms in this equation times -4 and add to the other equation:
40c+20p = 130
-32p+-20p = -112
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8c+0p = 18
8c = 18
c = 2.25 so the coffee is 2.25. Plug this into one of the two original equations and find p:
40c+20p = 130
40(2.25)+20p = 130
90+20p = 130
20p = 40
p = 2 the pastries are $2 each
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Try the other equation just for giggles:
8c+5p = 28
8(2.25)+5p = 28
18+5p = 28
5p = 10
p = 2 as you see, the pastries are still $2 ;-)