need help

[pearl tendon]

HOW to get to x=7??

[spiral zinc]

You should for the future try introducing more clear notation to not get confused. (Also use more space). In the first step you forgot brackets around the x+1 term (wich didnt have any impact as you still multiplied correctly after that). You also put the minus sign before the x+1 term and not the 3.

Since you already have the solution and i hope that you tried it yourself i have written down how you would do the answer correctly. This is mainly to show you how you could make equations more structured so those mistakes dont happen as easily. I wrote down at the end of the row what operations i made and always had both sides of the equation in the same line. Hope this helps you in the future.