Fist, write the equation as you see it:
7x + 12 = 9x
Next you have to put all the x’s on one side, whenever you move a number from one side to another it changes its sign (if it’s + it becomes - and if it’s - it becomes +)
7x - 9x = -12
Next add the x’s together:
-2x = -12
Then you must divide the two negive number which leave you with:
x = 6
The answer is x = 6.
Hope this helps!:)