So to find the answer u must multiply 20 x 5= 100
Answer: The age of the twins is 10 years.
Step-by-step explanation:
Suppose the age of older sister be x
Let the age of twins sister be x-9, as they are born after 9 years.
Product of their ages be
![x(x-9)(x-9)\\\\=x(x^2-18x+81)\\\\=x^3-18x^2+81x](https://tex.z-dn.net/?f=x%28x-9%29%28x-9%29%5C%5C%5C%5C%3Dx%28x%5E2-18x%2B81%29%5C%5C%5C%5C%3Dx%5E3-18x%5E2%2B81x)
Sum of their ages will be
![x+x-9+x-9\\\\=3x-18](https://tex.z-dn.net/?f=x%2Bx-9%2Bx-9%5C%5C%5C%5C%3D3x-18)
According to question,
![1861+3x-18=x^3-18x^2+81x\\\\x^3-18x^2+81x-3x+18-1861=0\\\\x^3-18x^2+78x-1843=0\\\\x=19](https://tex.z-dn.net/?f=1861%2B3x-18%3Dx%5E3-18x%5E2%2B81x%5C%5C%5C%5Cx%5E3-18x%5E2%2B81x-3x%2B18-1861%3D0%5C%5C%5C%5Cx%5E3-18x%5E2%2B78x-1843%3D0%5C%5C%5C%5Cx%3D19)
So, Age of older sister will be 19 years.
Age of the twins will be
![19-9=10\ years](https://tex.z-dn.net/?f=19-9%3D10%5C%20years)
Hence, the age of the twins is 10 years.
Answer:
look at explanation
Step-by-step explanation:
To solve all of these questions you just need to scale. While scaling you can divide or multiply.
1.
(divide by 4 to get unit rate)
unit rate = ![\frac{45km}{1hr}](https://tex.z-dn.net/?f=%5Cfrac%7B45km%7D%7B1hr%7D)
2. If it takes one hour to travel 40 miles, then we don't have to scale or anything. We know
, the answer is...
"It'll only take one hour to travel 40 miles. This is correct because the unit rate is
. "
3. Knowing that the constant speed of the plane is
, we can scale then add half of the unit rate to get our answer.
x 3 =
800 x 3 = 2400
then add half of unit rate which is
= 400
so, our answer is ![\frac{2800 km}{3.5 hours}](https://tex.z-dn.net/?f=%5Cfrac%7B2800%20km%7D%7B3.5%20hours%7D)
4.
<--- ( divided by 2)
( multiplied x 2.5) ---> ![\frac{15 km}{2.5 hrs}](https://tex.z-dn.net/?f=%5Cfrac%7B15%20km%7D%7B2.5%20hrs%7D)
To get an easier way to find the answer, if possible you can scale back farther than the 1 hour mark.
Elmer would take 2 and a half hours to ride 15 km.
5. The boys speed is
. All we need to do is divide by 2.
= 4
Answer:
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