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Lisa drove 240 miles, then increased her speed by 20 miles per hour for 540 miles. If the second part of the drive took 3 hours

Sever21 [200]

Let u be speed while Lisa drove 240 miles and t be the time in completing 240 miles.

We have been given that Lisa increased her speed 20 mph than initial speed over next 540 miles. So her speed on next 540 miles will be $u+20$ mph.

Further more we are given that she took 3 hours more to complete the next 540 miles of the trip than she took in completing initial 240 miles. So she took $(t+3)$ hours in completing next 540 miles.

Since we know $\text{Speed}=\frac{\text{Distance}}{\text{Time}}$

Now we will substitute our given values in our equation and find out the unknowns. After substitution we will get two equations and two unknowns.

$u=\frac{240}{t}.........(1)\\
\\
(u+20)=\frac{540}{t+3}........(2)$

Now we will substitute equation 1 in equation 2

$(\frac{240}{t}+20)=\frac{540}{t+3}$

Upon solving this equation, we get

$t=6$

Therefore, total time for Lisa to complete the entire trip is 6+6+3 = 15 hours.

And we know that total distance covered is 240+540 = 780 miles

Hence, average speed

$=\frac{\text{Total Distance}}{\text{Total Time}} = \frac{780}{15} = 52 \text{ miles per hour}$

6 0

3 years ago

Find the slope of the line containing (4, -2) and (-2, 3)

SashulF [63]

Answer:

-5/6

Step-by-step explanation:

3- -2 over -2-4

5/-6

4 0

4 years ago

Please help me with question

Mnenie [13.5K]

Answer:

4 hours 7 minutes

Step-by-step explanation:

Since Trevon takes 10 hours to clean the attic, he cleans 1/10, 10% or .1 of the attic per hour. Since Cody takes 7 hours to clean the attic, he cleans 1/7, 14.3% or .143 of the attic per hour.

Together, that means they clean .1 + .143 of the attic per hour. That's an hourly rate of:

.1 + .143 = .243

The portion of the attic they clean in x hours is .243x. We'd like to know how long it will take them to clean 100% or 1 of the attic. So:

.243x = 1 Divide each side by .243

x = 1/.243

x ≈ 4.115

Let's convert .115 to minutes by multiplying by 60

.115 * 60 = 6.9 round to 7 for 7 minutes

It will take them around 4 hours 7 minutes to clean the attic.

7 0

3 years ago

A rider sits on a motorcycle. The mortorcycle has a mass of 237 kilograms. Thee rider has a mass of 89 kilograms. what is the to