First, change your fraction 3/20 into a decimal.
How do we do that?
We would need to divide. Now, I always tell my students top number always go in the house when dividing, it is not always the "bigger" number.
Once when you divide, you would get the decimal, 0.15. Now, Bishon needs to sell at LEAST 0.3 of his collection, and he only sold 0.15 of his collection, and so since 0.15 is less than 0.3, selling 3/20 is not enough.
I hope this helps!