9=7x-13x-21 show step by step

First step is to combine like terms.

9 = 7x - 13x - 21 becomes 9 = - 6x - 21

Now add 21 to both sides to isolate our coefficient and variable.

- 6x - 21 + 21 = 9 + 21

The 21s on the left cancel out.

- 6x = 30

Now divide both sides by - 6 to isolate the variable.

x = 30 / - 6

x = - 5