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Dwayne drove 18 miles to the airport to pick up his father and then returned home. On the return trip he was able to drive an av

Nesterboy [21]

Answer:

30 mph

Step-by-step explanation:

Let d = distance (in miles)

Let t = time (in hours)

Let v = average speed driving <u>to</u> the airport (in mph)

⇒ v + 15 = average speed driving <u>from</u> the airport (in mph)

Using: distance = speed x time

$\implies t=\dfrac{d}{v}$

Create two equations for the journey to and from the airport, given that the distance one way is 18 miles:

$\implies t=\dfrac{18}{v} \ \ \textsf{and} \ \ t=\dfrac{18}{v+15}$

We are told that the total driving time is 1 hour, so the sum of these expressions equals 1 hour:

$\implies \dfrac{18}{v} +\dfrac{18}{v+15}=1$

Now all we have to do is solve the equation for v:

$\implies \dfrac{18(v+15)}{v(v+15)} +\dfrac{18v}{v(v+15)}=1$

$\implies \dfrac{18(v+15)+18v}{v(v+15)}=1$

$\implies 18(v+15)+18v=v(v+15)$

$\implies 18v+270+18v=v^2+15v$

$\implies v^2-21v-270=0$

$\implies (v-30)(v+9)=0$

$\implies v=30, v=-9$

As v is positive, v = 30 only

So the average speed driving to the airport was 30 mph

(and the average speed driving from the airport was 45 mph)

8 0

2 years ago

Read 2 more answers

100 points the right answer please the set designer for a play painted some background scenery on a large piece of plywood. He u

tiny-mole [99]

Answer:the answer is 14

Step-by-step explanation:

6 0

3 years ago

Please answer math questionS correctly for BRAINY

agasfer [191]

Hello there,

1st attachment:

So in order to find this answer. We need to know that in a CUBE there is L*W*H. Your answer would be A.) 1125 because when we do 1125 3 times (L*W*H). . . It give's us 3375.

2nd attachment:

Your answer would be D.) 5,832m³.

My reason I say this is because when you do 18 square root to 3. It will give you 5,832m³

3rd attachment:

Your correct answer would be 80mm³. So this is what I did. C wouldn't be the wrong answer because that answer is in "inches" and we want to find the answer in "mm³" So when we do 2*2*2. We get 8cm. We need to find the answer in "mm³" "8cm" converted in "mm³" would equal 80mm³.

Hope this helps.

~Jurgen

4 0

3 years ago

Read 2 more answers

what is Two times the sum of a number and four is no more than three times the sum of the number and seven decreased by four.

hjlf

2(x+4) ≤ 3(x+7 – b)
95% sure

5 0

3 years ago

Jeffery buys a shovel that costs 18 dollars and a pickaxe that costs 23 dollars. If sales tax is 6%, what is the total purchase

diamong [38]

Answer:

$2.46