Explain the Error Find the error in the solution, and then solve it correctly.

7x + 21 + 6x = 4

7x + 21 = -2

7x = -23

-23

7

(select) was subtracted from the left side, but (select) was subtracted from the right side. The

Subtraction Property of Equality states that you can subtract the same number from each side and the

equation will remain true. But 6x and 6 are not the same number (unless x is (select)).

X =