5,5.2,2
6,6,1,1
4,4,3,3
2,2,55
The first step for solving this problem is to multiply both sides of the bottom equation by -3.

Add the two equations together.
6x - 9y - 6x + 9y = 16 - 21
Eliminate the opposites.
-9y + 9y = 16 - 21
Remember that the sum of two opposites equals 0,, so the equation becomes the following:
0 = 16 - 21
Calculate the difference on the right side of the equation.
0 = -5
This means that the statement

is false for any value of x and y. That means that the answer to your question is (x,y) ∈ ∅,, or no solution.
Let me know if you have any further questions.
:)
I am not sure what the question is here. I can tell you how to find the percent of kids that developed influenza in that class. We can compare it to the 20% of students nationwide. There could many different questions that stem from the piece of information you gave.
To find the percent of kids that developed influenza in that class do 6÷15 which gives you
.4 and written as a percent would be 40%.
Please message me if you have any questions! Hope this helps!