Kindly upload the chart the text mentions.
The chart shows 25 fish on Wednesday
12 on Friday
20 on Saturday
and 10 on Sunday
We are asked to find the PERCENT DECREASE of Saturday compared to Wednesday.
So we recall the formula for percent decrease as:
(Initial Value - Final Value) / Initial Value times 100.
So, in our case the percent decrease becomes:
% decrease = (25 - 20) / 25 * 100 = 5/25 * 100 = 20%