Equations can be graphed.
Expressions can't.
(2x + 2y) is not an equation.
It can't be graphed.
It has no slope, and no intercept.
It's just an expression that stands for a number.
We can't find the number until we know the values of 'x' and 'y'.
If you told us a number that's equal to (2x + 2y), THEN we'd have
an equation, which could be graphed, and it would have a slope
and an intercept.
