To find the mid-way number we do this:
find the difference between the highest number and the lowest given number.
Divide the difference by 2
Add that number to the lowest number or subtract that number from the highest number.
20,000 - 4,632 = 15,362

= 7,684
4,632 + 7,684 = 12,316
or (we get the same number)
20,000 - 7,684 = 12, 316
12,316 is between 4,632 and 20,000
Answer:

Step-by-step explanation:
We have

Put the coordinates of the given points and check the inequality:
For (0; 5) → x = 0; y = 5

For (2; 4) → x = 2, y = 4

For (1; 3) → x = 1, y = 3

First divide 3.5 by 2 which equals 1.75. Then do 1.75*3 which equals 5.25. So he drinks 5.25 liters in one hour.
Let say the number is 0.5
Then, sum of this number will be 0.5+0.5=1
Now two is twice of 1.
Hence, it proved to be correct.
And difference between 5 and 1 is 4 which is less than 12. It also match the question condition.
Answer: The number is 1.