1. Polynomials are closed under the operations of addition and substraction mean that:
If we add two polynomials, the result is still a polynomial (so still in the set of polynomials)
Also, If we subtract 2 polynomials, the result is a polynomial.
2. Example: given the polynomials :

and

Addition example:


Subtraction example:

=

=

So both M(x)+N(x) and N(x)-M(x) are polynomials
The one in the middle is 12 for the median = 8
I'm going to convert all the values given to you in percentages, so hopefully you should be able to see the correct answer a little clearer. :)
Debbie said that 21/50 drink coffee in the morning. 21/50 can also be written as 42/100, and now that it's out of 100, it's basically a percentage. (42%).
Allen said that 45% of people drink coffee in the morning. His value is already written as a percentage, so we won't do anything with it.
Benny says that 0.495 of the people he surveyed drink coffee in the morning. 0.495 is the same as 49.5% (multiply it by 100 to get it in a percentage).
So, in Debbie's survey, 42% of people drink coffee.
In Allen's survey, 45% of people drink coffee.
In Benny's survey, 49.5% of people drink coffee.
Therefore, the answer is Benny's survey. :)
Answer:
0.5x+20=0.25x+30, m=40
Step-by-step explanation:
Blue: y=0.5x+20
Red: y=0.25+30
We’re looking for where the y (cost) is equal, so we can set the two equations to each other:
Isolate x:
0.5x+20=0.25x+30
0.5x+20-20=0.25x+30-20
0.5x=0.25x+10
0.5x-0.25x=0.25x+10-0.25x
0.25x=10
x=40
m= 40