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3 years ago

15

The amount of money it takes to fill up a gas tank varies directly with the number of gallons bought. It cost $21.87 to fill up

a car with gasoline with 9 gallons of gasoline. What is the constant of variation?

2 answers:

Snowcat [4.5K]3 years ago

8 0

I think the answer is

2.43

Arisa [49]3 years ago

6 0

Answer:

$2.43 per gallon of gas.

Step-by-step explanation:

We have been given that the amount of money it takes to fill up a gas tank varies directly with the number of gallons bought.

We know that the equation for two directly proportional quantities is in form: $y=kx$ , where,

k = The constant of variation and y is directly proportional to x.

To find the constant of variation for our given equation, we will substitute the given values in above equation as:

$\$21.87=k*9\text{ gallons}$

Let us divide both sides of our equation by 9 gallons.

$\frac{\$21.87}{9\text{ gallons}}=\frac{k*9\text{ gallons}}{9\text{ gallons}}$

$\frac{\$2.43}{\text{ gallon}}=k$

Therefore, the constant of variation is $2.43 per gallon of gas.

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Can someone help me with these and show the work also?

Snezhnost [94]

QUESTION:

Simplify each expression

ANSWER:

1.) $\green{{- 8n}}$

2.) $\green{{- 2b - 60}}$

3.) $\green{{- 10x - 14}}$

4.) for number 4 study my step-by-step explanation so you can answer that

STEP-BY-STEP EXPLANATION:

1.) First, If the term doesn't have a coefficients, it is considered that the coefficients is 1

WHY?

Learn why:

Why is it considered that the coefficient is 1?

Remember that any term multiplied by $\blue{{1}}$ remains the same :

$\blue{{1}}$ ${× x = x}$

Step 1:

The equality can be read in the other way as a well, so any term can be written as a product of $\blue{{1}}$ and itself:

${x = }$ $\blue{{1}}$ ${× x}$

Step 2:

Usually, we don't need to write multiplacation sign between the coefficient and variable, so the simple form is:

${x = 1x}$

This is why we can write the term without the coefficient as a term with coefficient ${1}$

Now let's go back to solving as what i said if a term doesn't have a coefficient, it is considered that the coefficient is 1

${n - 9n}$

$\red{{1}}$ ${n -9n}$

Second, Collect like terms by subtracting their coefficients

$\red{{1n - 9n}}$

$\red{{( 1 - 9)n}}$

Third, Calculate the difference

how?

Keep the sign of the number with the larger absolute value and subtract the smaller absolute value from larger

$\red{{1 - 9}}$

$\red{{- (9 - 1)}}$

Subtract the numbers

- ( $\red{{9 - 1}}$ )n

- $\red{{8}}$ n

$\green{\boxed{- 8n}}$

2.) First, Distribute - 6 through the parentheses

how?

Multiply each term in the parentheses by - 6

$\red{{- 6(b + 10)}}$

$\red{{- 6b - 6 × 10}}$

Multiply the numbers

- ${6b}$ - $\red{{6 × 10}}$

- ${6b}$ - $\red{{60}}$

Second, Collect like term

how?

Collect like terms by calculating the sum or difference of their coefficient

$\red{{- 6b + 4b}}$

$\red{{(- 6 + 4)b}}$

Calculate the sum

$\red{{(- 6 + 4)}}$ b

$\red{{-2}}$ b

$\green{\boxed{- 2b - 60}}$

3.) First, Distribute 2 through parentheses

how?

Multiply each term in the parentheses by 2

$\red{{2(x - 5)}}$

$\red{{2x - 2 × 5}}$

Multiply the numbers

${2x -}$ $\red{{2 × 5}}$

${2x -}$ $\red{{10}}$

Second, Distribute - 4 through the parentheses

how?

Multiply each term in the parentheses by - 4

$\red{{- 4(3x + 1)}}$

$\red{{- 4 × 3x - 4}}$

Calculate the product

- $\red{{4 × 3}}$ x - 4

- $\red{{12}}$ x - 4

Third, Collect like terms

how?

Collect like terms by subtracting their coefficient

$\red{{2x - 12x}}$

$\red{{(2 - 12)x}}$

Calculate the difference

$\red{{(2 - 12)}}$ x

$\red{{- 10}}$ x

Fourth, Calculate the difference

how?

Factor out the negative sign from the expression

$\red{{- 10 - 4}}$

$\red{{- (10 + 4)}}$

Add the numbers

- ( $\red{{10 + 4}}$ )

- $\red{{14}}$

$\green{\boxed{- 10x - 14}}$

That's all I know sorry but I hope it helps :)

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