We have to isolate b to be alone.
Soooo first we divide both sides by 6
-81 = b6
÷6 = ÷6 The right side cancels out and gets the b alone. While we solve the right side of the equal sign.
-81 ÷ 6 = -13.5
So this means we isolated b alone!
b = -13.5
Our final answer is..
b = -13.5
:)