First you combine the x. 6x+(1)x = 7x
-1+7x=-1
Then move the -1 to the other side, changing the sign( if it is positive make it negative. If it is negative make it positive) -1+1 = 0
7x=0
Next you divide the 7 by 0 because you undo the multiplication ( the opposite of multiplication is division) 7/0 = 0
x=0
Hope this helps!!❤️