First, change everything into minutes.
12 noon is 12 by 60 which = 720 minutes.
9am is 9 by 12 which = 540 minutes.
X is now your number of minutes before noon.So noon - x is the next step:
720 - x
20 minutes ago it was 720 - x - 20
720 - x - 20= 540 + 3x (3x because you're looking for 3 times as many minutes)
720 - 20 - 540=4x (you combine all the like numbers and variables)
160 = 4x
160/4= x
40 = x
Your answer is 40 minutes