My guess would be A ! Hope this helps
We are given with an 18 student class that is working a project worked by pairs. Each pair works on a project. In this case, there are 9 teams of 2 individuals working on a single project. Hence for a year or school year, there are 9 projects accomplished each time.
-30-5x=-4x-6(5+4x)
First, you need to use the distributive property on the right to get -30-5x=-4x-30-24x
Then, you can add like terms to get -30-5x=-30-28x
Then, you can add 30 to both sides and add 5x to both sides to get 0=-23x
Finally, you divide both sides by -23 to get 0=x
Answer: No, the friend is correct. In any function, each input value can only lead to one output value. When you input 3 for the x-values, you would get two output values because 3 is included in both equations. To fix this, you need to have the 3 not included in one of the equations.
For example, you could say 
or 
because the input value of 3 would not be included twice.
If you look at the attached screenshot, you will see that if you keep your friend's function, inputting 3 will result in two outputs of 4 and -3, so therefore, 
cannot represent a piecewise function.
