my problem is -8=6x+16 would the answer be x=5 ?

No. If you plug x=5 into the right hand side you get:

6x+16 = 6x5+16 = 46, which does not equal the left hand side.

I suggest you start by subtracting 16 from both sides of the equation, and go from there. What do you get?

You need to find a number that multiplies by 6, then after adding 16 equals -8.

The answer is x=(-4).

You get this answer because 6 x (-4) = -24, changing the equation to -8=(-24)+16 and -24+16 = (-8)