So first, lets understand this problem with an equation. This is what i got:
\(\frac{x}{x+1}\cdot\frac{x+1}{x+2} ...\frac{x+19}{x+20}=3\)
now we cancel. You see by cross canceling, the x+1's dissapear as all of them do and you are left with
\(\frac{x}{x+20} = 3\)
well, you might think that since it has to be a positive fraction and x has to be negative, this is wrong, BUT keep in mind, if both x in the numerator and denominator or negative, the fraction is a postive. so simplify this equation.
\(x = 3x+60\) multiply both sides by \(x+20\)
\(2x=-60\) subtracting x on both sides and moving the 60 over.
you will get x = -30, so the first fraction will be\(\frac{30}{31}\),which will be your answer!