a +/- b1 + b2 + b3 = ? ? ? ?

I saw this sticker on the rear window of a car the other day.
At first I was like: Ooo, look at the pretty colors.
Then I realized what it was and went: Hey, wait a minute.
Then I thought: Really?To be fair, I don’t know that this is an official campaign sticker. But…Someone Somewhere thought it was a good idea.