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3 years ago

A total of 20 quarters and nickels add up to $4.00. How many nickels are there?

Mathematics

1 answer:

mariarad [96]3 years ago

8 0

Answer:

5 nickels

Step-by-step explanation:

You can setup and solve a system of equations, or you can solve by trial and error until you get the correct answer.

Here is the solution by trial and error.

If all 20 coins are quarters, the value is 20 * $0.25 = $5

That is too much value.

Let's try 16 quarters. 16 quarters are worth 16 * $0.25 = $4.

That is the correct value, but it is only with quarters, and only 16 of them.

We need fewer quarters than 16.

Try 12 quarters: 12 * $0.25 = $3.00

The number of nickels is: 20 - 12 = 8

8 nickels are worth 8 * $0.05 = $0.40

12 quarters and 8 nickels are worth $3.00 + $0.40 = $3.40

There are 20 coins, but the value is too low.

The number of quarters is between 12 and 16.

Try 14 quarters and 6 nickels:

14 * $0.25 + 6 * $0.05 = $3.50 + $0.30 = $3.80

We are closer to $4 but not there yet.

Try 15 quarters and 5 nickels.

15 * $0.25 + 5 * $0.05 = $3.75 + $0.25 = $4

The total value is $4 and there are 20 coins. This is the answer.

15 quarters and 5 nickels works.

Answer: 5 nickels

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kirill [66]

To tell if an equation has infinite solutions, the equation will be equal to each other.

For example,

x = x
x + 1 = x + 1
x - y = x - y

And so on...

And in special cases,

0x = 0
0x = 0(y + 1)

They have infinite solutions because there's no constant to determine the variable.

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3 years ago

Simplify 8^x/4^y x 2^z

Lera25 [3.4K]

Answer:

The answer is 8x.

Step-by-step explanation:

It is 8x.

EXCEPT,

Is it $2^{z}$ or $2^{2}$

If it is $2^{z}$ then the answer is $\frac{2^{3x+z} }{4}$

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2 years ago

Gnesinka [82]

Answer:

C. –x + 8y = 56

Step-by-step explanation:

Write in standard form.

x − 8 y = − 56

This is a linear function in the slope - intercept form:

y = m x + b and we need a standard form:

a x + b y = c

y = 1/8 x + 7 / * 8 ( we will multiply both sides of equation by 8 )

8 y = x + 56

- x + 8 y = 56 / * ( - 1 )

x - 8 y = - 56

The equation is y = 1/8x + 7

Standard form equation is Ax + By = C, where A > = 0.

First eliminate the fractions by multiplying the equation by 8

8y = x + 56

Subtract x from each side

-x + 8y = 56

SInce x coeficient can't be negative multiply the equation by negative one.

x - 8y = -56

4 0

3 years ago

A ship leaves port at noon and has a bearing of S29oW. The ship sails at 20 knots. How many nautical miles south and how many na

ira [324]

Answer:

Approximately $58.2\; \text{nautical miles}$ (assuming that the bearing is ${\rm S$29^{\circ}$W}$ .)

Step-by-step explanation:

Let $v$ denote the speed of the ship, and let $t$ denote the duration of the trip. The magnitude of the displacement of this ship would be $v\, t$ .

Refer to the diagram attached. The direction ${\rm S$29^{\circ}$W}$ means $29^{\circ}$ west of south. Thus, start with the south direction and turn towards west (clockwise) by $29^{\circ}$ to find the direction of the displacement of the ship.

The hypothenuse of the right triangle in this diagram represents the displacement of the ship, with a length of $v\, t$ . The dashed horizontal line segment represents the distance that the ship has travelled to the west (which this question is asking for.) The angle opposite to that line segment is exactly $29^{\circ}$ .

Since the hypotenuse is of length $v\, t$ , the dashed line segment opposite to the $\theta = 29^{\circ}$ vertex would have a length of:

$\begin{aligned}& \text{opposite (to $\theta$)} \\ =\; & \text{hypotenuse} \times \frac{\text{opposite (to $\theta$)}}{\text{hypotenuse}} \\ =\; & \text{hypotenuse} \times \sin (\theta) \\ =\; & v\, t \, \sin(\theta) \\ =\; & v\, t\, \sin(29^{\circ})\end{aligned}$ .

Substitute in $\begin{aligned} v &= 20\; \frac{\text{nautical mile}}{\text{hour}}\end{aligned}$ and $t = 6\; \text{hour}$ :

$\begin{aligned} & v\, t\, \sin(29^{\circ}) \\ =\; & 20\; \frac{\text{nautical mile}}{\text{hour}} \times 6\; \text{hour} \times \sin(29^{\circ}) \\ \approx\; & 58.2\; \text{nautical mile}\end{aligned}$ .

7 0

2 years ago

Matthew plays soccer for h hours per day for five days in a row. Over the weekend, he played in a soccer tournament for a total

Goryan [66]

T=(h*5)+6.5 should be it because it is the number of hours multiplied by 5 days and then you add the 6.5 hours

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3 years ago

Read 2 more answers