Juice guy is bad at simple math

Date: 5/7/2016

I was going to university like normal. In my way I meet an old friend (AM) and he was with another friend. I stop to say hi and we talk for a while. Then before we separate I suggest that we buy cane juice before we leave. In this dream, it was obvious that cane juice costs 3 pounds. When time came to pay they all seemed very confused with the Math (to a frustrating extent). It's pretty obvious to me that the total is 3*3 which is 9 pounds. I pull out 5 pounds and ask (AM) to a add 4 pounds so he does, albeit confused. I give the 9 pounds to the man in the store, to which he responds by looking at them in a dumb manner (as if I've made some mistake). I keep trying to convince them all that my math was correct (for some reason they were all on his side). I begin telling them that we are 3 people and that each juice costs 3 pounds so that's a total of 9 pounds, but the store guy would say that that's just wrong and tries to convince me that it's actually 15 pounds. When I get tired I ask him whether I could explain it to him on paper, so he said sure. He grabbed a pen and paper and proceeded to explain to me first. He said "if you bought one juice" writing down the word juice, "and say you bought a chicken sandwich" he added, while writing down "+ chicken", "and say you bought one sauce" he added, writing down "+ sauce", at which point I was growing impatient of his pointless and obvious argument. I was thinking about using his same argument to convince him about my case. I'm planning to say to him: "say you bought one juice, then you bought one juice, then you bought one juice, then you have juice+juice+juice". Which seemed simple enough. When he gave me the pen and paper and I proceeded to write down my explanation for him I used a different terminology for some reason. I said: "so we are three people", he nods, I add: "each of us has three eyes" and as I was about to continue with my explanation he interrupted me (I'm not sure why I said that we had 3 eyes, maybe I was just using it to explain multiplication to him, although I could have used a number of more other realistic things instead. I think in my dream that seemed like the natural thing to say for some reason). Anyway he interrupts me by saying: "now you can't just say that you have three eyes and continue speaking.. How exactly do you have three eyes." At which point I'm so disappointed because he missed the whole point and I'm about to give up and just pay whatever he asks for and leave as I was getting late. Throughout the whole dream I was very certain at start but as I stood there I became questioning myself more and more because all three of them thought I was wrong, which is not a good thing.