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3 years ago

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Carole's car averages 13.2 mi/gal in city driving and 25.3 mi/gal in highway driving. If she drove a total of 396.0 mi on 19 gal

of gas, how many of the gallons (to the nearest gallon) were used for city driving?

1 answer:

nika2105 [10]3 years ago

5 0

Answer:

7 gallons were used for city driving.

Step-by-step explanation:

I am going to solve this question by a system of equations.

I am going to say that:

x is the number of gallons driven in the city.

y is the number of gallons driven in the highway.

19 gal of gas

This means that $x + y = 19$

Carole's car averages 13.2 mi/gal in city driving and 25.3 mi/gal in highway driving. If she drove a total of 396.0 mi.

This means that $13.2x + 25.3y = 396$

How many of the gallons (to the nearest gallon) were used for city driving?

This is x

From the first equation, i will have

$y = 19 - x$

Replacing in the second equation

$13.2x + 25.3y = 396$

$13.2x + 25.3(19 - x) = 396$

$13.2x - 25.3x = 396 - 480,7$

$12.1x = 84.7$

$x = \frac{84.7}{12.1}$

$x = 7$

7 gallons were used for city driving.

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<em><u>Solution:</u></em>

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Cost of 1 granny smith apple = $ 0.25

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Therefore,

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<em><u>Substitute eqn 3 in eqn 2</u></em>

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Step-by-step explanation:

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(A)

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(B)

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Th matrix <em>B</em> represents the amount of each order for the next week. Then matrix <em>B</em> is:

$B=\left[\begin{array}{ccc}11&22&44\end{array}\right]$

(C)

Add the two matrix <em>A</em> and <em>B</em> as follows:

$A+B=\left[\begin{array}{ccc}10&20&40\end{array}\right]+\left[\begin{array}{ccc}11&22&44\end{array}\right]\\=\left[\begin{array}{ccc}(10+11)&(20+22)&(40+44)\end{array}\right]\\=\left[\begin{array}{ccc}21&42&84\end{array}\right]$

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