Yes and they will always be coplanar.
The answer you want is: Product.
4+2x=10
2x=10-4
2x=6
X=6/2
X=3
The first thing he has to do is take that "minus" sign through the parentheses containing the second polynomial. Some students find it helpful to put a " 1 " in front of the parentheses, to help them keep track of the minus sign. Here's what the subtraction looks like, when working horizontally.