Remove the brackets on the left.
4 + 10x - 16 = ax + b
10x - 12 = ax + b
If a = 10 and b = -12 then x can be anything and equality would be true.
So for example let x = 400
10*400 - 12 = 10*400 - 12
4000 - 12 = 4000 - 12
3988 = 3988
You could put in any number you wanted to for x and the results would be equality but meaningless.
