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The cafeteria sells each apple at one price and each banana at another price. For 5 apples and 3 bananas Dan pays $5.70. For 3 apples and 5 bananas Chris pays $4.70. The price of one apple is how much more then the price of one banana, in cents?

In this question, why do you multiply by 5 to the top equation and 3 to the bottom equation?

1 Answer

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Answer: In this question, we are trying to find the difference in price between one apple and one banana. We can set up a system of two equations with two variables to represent the information given in the problem. Let x be the price of one apple in cents and y be the price of one banana in cents.

The first equation represents the information that Dan paid $5.70 for 5 apples and 3 bananas:

5x + 3y = 570

The second equation represents the information that Chris paid $4.70 for 3 apples and 5 bananas:

3x + 5y = 470

We can use these equations to solve for the value of x (the price of one apple) in terms of y (the price of one banana).

We can use the first equation and solve for x:

5x = 570 - 3y

x = (570 - 3y)/5

We can then substitute this expression of x into the second equation:

3((570 - 3y)/5) + 5y = 470

By multiplying both sides of the equation by 5 and 3 respectively, we can get the equation in a form that we can solve for y and then substitute back for x.

We can solve for y by subtracting 3((570 - 3y)/5) from both sides:

5y = 470 - 3((570 - 3y)/5)

Expanding and simplifying the right side of the equation:

5y = 470 - 3(114 - y)

5y = 470 - 342 + 3y

y = (470 - 342)/8

We can substitute this value of y back into the first equation and solve for x

x = (570 - 3y)/5

x = (570 - 3(470 - 342)/8)/5

x = (570 - 441)/5

Therefore, the price of one apple is (570 - 441)/5 = 129 cents more than the price of one banana.

Explanation:

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