What do i do to calculate the 25% mean of 50 variables? Like, how many do I take away from the smallest and largest sides?

Remove the lowest 25 percent, and the highest quartile. So 25 percent of 50 is 13 (or 12, it shouldn't make any difference. Your instructor or text probably gave you a rule for rounding, but honestly, it wont matter. Life is not precise in statistics).