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DerKrebs [107]
3 years ago
15

Mary has a collection of nickels and quarters for a total of $4.90. If she has 42 coins in total, how many of each kind are ther

e?
Mathematics
1 answer:
damaskus [11]3 years ago
5 0

Answer:

14 quarters and 28 nickels

Step-by-step explanation:

System of Equations where x = number of quarters and y = number of nickels

(1) equation with value of each coin

    0.25(x)+0.05(y) = 4.90

(2) total number of coins

    x + y = 42

Solve system of equations using either substitution or elimination

(elimination multiplying equation 2 by -0.5)

.25(x) + 0.05(y) = 4.90

-0.05(x) - 0.05(y) = 42 * (-0.05)

(3) Resulting equation

.20(x) = 2.8

x = 14

plug x into equation 2

14 + y = 42

y = 28

There are 14 quarters and 28 nickels in Mary's collection.

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Ethan repairs household appliances like dishwashers and refrigerators. For each visit, he charges $25 plus $20 per hour of work.
dalvyx [7]

Answer:the independent variable is x, the number of hours of work.

The dependent variable is y, the total charge for x hours of work.

Step-by-step explanation:

A change in the value of the independent variable causes a corresponding change in the value of in dependent variable. Thus, the dependent variable is is output while the independent variable is the input

For each visit, he charges $25 plus $20 per hour of work. The linear expression that represents the total amount of money that Ethan earns per visit is y = 25 + 20x.

Since the total amount charged, y depends on the number of hours of work, x, it means that the dependent variable is y and the independent variable is x

4 0
3 years ago
What is the recursive formula for this geometric sequence?<br> -2, -16, -128, -1024,
FinnZ [79.3K]
<h3>Answer: Choice A</h3>

The first line shown in choice A is a_1 = -2 which means "the first term is -2"

The next line in choice A means "the nth term (a_n) is found by multiplying the prior term (a_{n-1}) by 8". Put another way: multiply each term by 8 to get the next term.

first term = -2

second term = 8*(first term) = 8*(-2) = -16

third term = 8*(second term) = 8*(-16) = -128

fourth term = 8*(third term) = 8*(-128) = -1024

and so on.

3 0
4 years ago
Read 2 more answers
A scientist wishes to estimate the mean breaking strength of a certain type of steel rod within 3.0 psi with 95% confidence. Bas
yaroslaw [1]

Answer:97 rods

Step-by-step explanation:

The number of steel rods for 95% confidence level

n=\left ( \frac{Z_\frac{\alpha }{2}\times \hat{\sigma }}{E} \right )^2

Z_\frac{\alpha }{2}=1.96

E=3

\hat{\sigma }=15

Substituting values

n=\left ( \frac{1.96\times 15}{3}\right )^2

n=96.04\approx 97

Thus 97 rods is tested

6 0
4 years ago
(3, -2) belongs to the solution set of the system of inequalities given below:
Gennadij [26K]

Answer:

true

Step-by-step explanation:

no explanation but its true.

3 0
3 years ago
What is the answer for 10x+75+5x=110? And how do you get it?
cestrela7 [59]
Okay, let's add the two x values.
10x + 75 = 5x = 110
15x + 75 = 110

Now let's minus 75 from each side.
15x = 35

Now let's divide each side by 15.
x = 2.333333333
8 0
3 years ago
Read 2 more answers
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