Okay, I think I'm starting to get it. What Amphibious is trying to say is that u take 30lbs, but 20lbs more for men, but if u are a girl u don't belch so you add half especially if you have a brother, unless your brother is a girl too, then you add twice that (16lbs) unless your girl brother belches, in which case you end up with only 8. So, clearly, just as Amphibious was trying to say, the answer is 29, but only if u lift at gym home, if u work outside then it it doesn't matter if u are a girl, unless you are french polynesian, in which case the answer is 37.5.
But, there could be another interpretation. If u follow Nietzche, then you get that 20 reps inside is less than half of 30lbs in home, unless on the floor, in which case 21 reps is more than 28, because the air isn't as good on the floor, unless u are by a window, and your brother isn't farting outside the window. If he is then the air on the floor is better, which makes the 20lbs worse than 37 for the polynesian girl at least.
I hope that clears things up a bit.