I'm very confused on how to do this,

Multiply 5 to 2b + 8 and you'll get 10b + 40 = -12. Subtract the 40 from -12 and you'll get -52. -52/10 = -5.2 =b

Ok, so first off, you'd want to isolate the variable. You'll start that multiplying 5 on each side, giving you an outcome of 2b + 8 = -60.

Then, you'll subtract 8 on both sides, giving you 2b = -68.

Finally you will divide both sides of the equation by 2, making b = -34.

I hope this helped you in some way. Thanks for your time!