Prepositional looey-rithmetic is a bitch ... is that "on", "of", "in", "at", "below", "behind", "in front of". etc.? One needs to know these things since it could make the answer anywhere from -12 to 187.
Sheeze!!
I know he's not that stupid... he's just trying to confuse the thread - but he's given an opportunity to explain in ten ways to every lurker how clear it is - and he's shown himself to be quite stupid in the process.