math word problem

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4.3.11

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On​ Monday, Luis picked up seven scones and four large coffees for the office staff. He paid $ 26.28 .On​ Tuesday, Rachel picked up six scones and five large coffees for the office staff. She paid $ 25.37.

What is the cost of one​ scone? What is the cost of one large​ coffee?

Answer 1

Let S = price of scones and C = price of coffee.

Luis: 7S + 4C = 26.28

Rachel: 6S + 5C = 25.37

There is NO EASY way to solve this set, i.e. any solution is messy.

The least nuisance is to use determinants which you may not know about.

Next, I would advise: multiply the first equation by 5 and the second by 4.

Then subtract to eliminate the C.

Solve for S and use that value to get C.