The answer is -1 because this is basically a two step equation. First you set it up as
x-7=2x-6. Then, you add( because you do the opposite of the number ex. -6 is the opposite of 6) the number without the variable first (doesn't matter which one you do as long as you do it to both sides) what i did was i added 7 to both sides to get
x= 2x+1 then i subtracted 2x from both sides to get -x=1. And this is the tricky part, x con't end up to be a negative so you divide both sides by negative 1 because every variable has a number infront of it even if is not seen ( then it is 1) and since it is negative x it it -1. Therefore, the answer is -1.