Amanufacturer produces bolts of a fabric with a fixed width. the quantity q of this fabric (measured in yards) that is sold is a function of the selling price p (in dollars per yard), so we can write q = f(p). then the total revenue earned with selling price p is r(p) = pf(p). (a) what does it mean to say that f(20) = 10,000? when the price of fabric is $20/yard, 10,000 yards will be sold. when the price of fabric is $425/yard, 20 yards will be sold. there are 425 total yards of fabric and $20 to spend on it. when the price of fabric is $20/yard, 425 yards will be sold. there are 10,000 total yards of fabric and $425 to spend on it. what does it mean to say that f '(20) = −425?