What is the speed limit? It is hard enough going the speed limit now you have to figure it out too? What if you solve it wrong? All the people who never took algebra would be getting a lot of tickets. The answer is 45 mph.
I said this to my Algebra Teacher once, she did not get it. That's okay, I didn't get Algebra either. My Geometry teacher had a far better sense of humor. Algebra never make sense until after I took Geometry any way.