You would transform 5x + 2x into the same term with the associative property, adding like terms. If you subsitute the different values into the expressions you notice that both have a rate of change of 7 like an arithmetic sequence. To see if any value will make the two expressions equal you make them equal to each other.
5x + 2x = 7x -1
7x = 7x - 1
0 = -1
No they will never have be a solution to both expressions to make them equal because they're parallel to each other.
