Which expression is equivalent to 5x − 2x + 6 and why?
5x + 4, because 5x − (2x − 6) = 5x + 4
13x, because 5x − 2x + 6 = 5x + 8 = 13x
6 + 3x, because (5x − 2x) + 6 = 3x + 6 = 6 + 3x
9x, because 5x − 2x + 6 = 3x + 6 = 9x