Let's write some equations.
Mingwei's distance from Town A after
![x](https://tex.z-dn.net/?f=x)
hours from 8:00 is
![45x](https://tex.z-dn.net/?f=45x)
.
Ali's distance from Town B after
![x](https://tex.z-dn.net/?f=x)
hours is
![30x-20](https://tex.z-dn.net/?f=30x-20)
, since he doesn't start walking for 40 minutes.
When Mingwei's distance is twice Ali's, they've met up (since their distance from Town A is twice their distance from Town B).
So, this gives
![45x=60x-40](https://tex.z-dn.net/?f=45x%3D60x-40)
, so
![15x=40](https://tex.z-dn.net/?f=15x%3D40)
, so
![x=\frac{40}{15} = \frac{8}{3}](https://tex.z-dn.net/?f=x%3D%5Cfrac%7B40%7D%7B15%7D%20%3D%20%5Cfrac%7B8%7D%7B3%7D)
, so the time is 10:40.
After
![\frac83](https://tex.z-dn.net/?f=%5Cfrac83)
hours, Mingwei has traveled
![45 * 8 / 3 = 120](https://tex.z-dn.net/?f=45%20%2A%208%20%2F%203%20%3D%20120)
kilometers while Ali has traveled sixty, so the distance between the towns is
![180](https://tex.z-dn.net/?f=180)
kilometers.
well if 18 out of 25 like it, then the remaining 7 doesn't like it, namely 7 out of 25.
if we take 25 to be the 100%, what is 7 off of if in percentage?
![\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 25&100\\ 7&x \end{array}\implies \cfrac{25}{7}=\cfrac{100}{x}\implies 25x=700\implies x=\cfrac{700}{25}\implies x=28](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Barray%7D%7Bccll%7D%20amount%26%5C%25%5C%5C%20%5Ccline%7B1-2%7D%2025%26100%5C%5C%207%26x%20%5Cend%7Barray%7D%5Cimplies%20%5Ccfrac%7B25%7D%7B7%7D%3D%5Ccfrac%7B100%7D%7Bx%7D%5Cimplies%2025x%3D700%5Cimplies%20x%3D%5Ccfrac%7B700%7D%7B25%7D%5Cimplies%20x%3D28)
D. 10 is your answer.
In order to solve a proportion, you cross multiply.
In this case it will be 40=4x
Solve for x is 10. Therefore D is your answer.
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