Comma for independent clauses?

Hi. Would you say the punctuation mark "comma" is needed before the conjunction "and" in the following sentence? I dont' know it is makes a difference of any sort but I want to let you know that I feel/think the implications (effect?) of the preposition phrase "At this point" is shared between the clause that comes before the conjunction "and" and the clause that comes after it, and thus I feel not having a comma might be correct, too, in addition to having a camma before "and" in the following sentence. (Not sure I have written correctly to reflect what I wanted to say, though.)

(looking at a graph) Let's pretend the letters "XXX" represent a particular price and the letters "YYY" represent a certain number of pens, based on the point on the graph.

At this point, the price of the pens is XXX and the number of pens produced is YYY.