3/20 = 15%
A share of 3/20, or 15%, might describe how many people in a group prefer a certain snack. You might also see a 15% discount on a store tag.
To picture it quickly, imagine 20 equal pieces and shade 3 of them. You can also think of it as a little less than one-sixth of the whole.
A common mix-up is thinking that 15% off means the final price is 15% of the original price. It means the price is reduced by that amount, so most of the original price remains.