At a cafeteria, Mary orders two pieces of toast and a bagel, which comes out to $\$3.15$. Merry orders a bagel and a muffin, which comes out to $\$3.30$. Meery orders a piece of toast, two bagels, and three muffins, which comes out to $\$9.15$. How many cents does one bagel cost?

Respuesta :

Answer:

A bagel costs $1.55, so that would be 155 cents

Step-by-step explanation:

Given Info:

x = cost of a piece of toast

y = cost of a bagel

z = cost of a muffin

2x + y = 3.15

y + z  = 3.30

x + 2y + 3z = 9.15

Calculations:

2x + y - (y + z ) = 3.15 - 3.30

2x - z = -0.15

-z = -0.15-2x

z = 0.15+2x

y = 3.15 - 2x

x + 2y + 3z = 9.15

x + 2(3.15 - 2x) + 3(0.15 + 2x) = 9.15

x + 6.3 -4x + 0.45 + 6x = 9.15

3x + 6.75 = 9.15

3x = 2.4

x = 0.80 cents per piece of toast

2x + y = 3.15

2(0.80) + y = 3.15

1.60 + y = 3.15

y = 1.55

So a bagel costs $1.55

One bagel costs 155 cents.

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This question is solved using a system of equations.

I am going to say that:

  • x is the cost of a toast.
  • y is the cost of a bagel.
  • z is the cost of a muffin.

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Two pieces of toast and a bagel costs $3.15.

This means that [tex]2x + y = 3.15[/tex]

Since we want to find the cost of a bagel, we write x as a function of y, so:

[tex]2x = 3.15 - y[/tex]

[tex]x = -0.5y + 1.575[/tex]

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A bagel and a muffin costs $3.30.

This means that:

[tex]y + z = 3.3[/tex]

Since we want y:

[tex]z = 3.3 - y[/tex]

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Piece of toast, two bagels and three muffins cost $9.15.

This means that:

[tex]x + 2y + 3z = 9.15[/tex]

We have x and z as functions of y, so:

[tex]-0.5y + 1.575 + 2y + 3(3.3 - y) = 9.15[/tex]

[tex]-0.5y + 1.575 + 2y + 9.9 - 3y = 9.15[/tex]

[tex]-1.5y + 11.475 = 9.15[/tex]

[tex]1.5y = 2.325[/tex]

[tex]y = \frac{2.325}{1.5}[/tex]

[tex]y = 1.55[/tex]

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In cents, one bagel costs 100*1.55 = 155.

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