Using chips

R-2

Which one works and why? \
Student A:

2x+4+6x-5+7x+3=17x

-No add-ons or coins
-Just add numbers then x at the end



Student B:

2x+4+6x-5+7x+3=15x+2

-Added together. 2x+6x=7x=15x



**If x= 1, then both would be right. 

Questions:
If problems are the same, why 2 answers?
Where is the +2 from?


Rule:
Never assume x=
Don't mix apples and oranges (strips and the chips, bags and the coins, x and add-ons)
Always show the add-on Don't mix the constant or an add-on