Given:
Cost of a jacket = $20
Then sells it to customers for 80% more than.
To find:
The selling price of the jacket
Solution:
We have,
Cost of a jacket = $20
Selling price = cost + 80% of cost
= ![20+\dfrac{80}{100}\times 20](https://tex.z-dn.net/?f=20%2B%5Cdfrac%7B80%7D%7B100%7D%5Ctimes%2020)
= ![20+\dfrac{8}{1}\times 2](https://tex.z-dn.net/?f=20%2B%5Cdfrac%7B8%7D%7B1%7D%5Ctimes%202)
= ![20+16](https://tex.z-dn.net/?f=20%2B16)
= ![36](https://tex.z-dn.net/?f=36)
Therefore, the selling price of the jacket is $20.
Answer: p(6) represents how the number of bacteria after 6 days.
Simply replace each x with 6 to go from the first sentence to the answer shown in bold above.
La ès pasanodáo mel lachillo
If
is a number that is both divisible by 4 and 5, then
![\begin{cases}x\equiv0\pmod4\\x\equiv0\pmod5\end{cases}](https://tex.z-dn.net/?f=%5Cbegin%7Bcases%7Dx%5Cequiv0%5Cpmod4%5C%5Cx%5Cequiv0%5Cpmod5%5Cend%7Bcases%7D)
4 and 5 are coprime, so we can use the Chinese remainder theorem to solve this system and find that
is a solution to the system, where
is any integer. Simply put, any multiple of 20 fits the bill.
Now, there are 11 numbers between 100 and 300 that are divisible by 20 (100, 120, 140, and so on). We have
when
, so the sum we want to compute is
![\displaystyle\sum_{n=5}^{15}20n=\boxed{2200}](https://tex.z-dn.net/?f=%5Cdisplaystyle%5Csum_%7Bn%3D5%7D%5E%7B15%7D20n%3D%5Cboxed%7B2200%7D)