Rational Number are set of numbers that can be written as a/b where a and b are integers, but b is not equal to 0; an integer or a fraction; for example: 6 can be expressed as 6/1 and 0.5 can be expressed as 1/2.
Since we know 85% of the students participated last year we can assume the same amount will participate this year so to find the answer you simply do the total number of students (320) multiplied by 85% or .85 to get the best guess of how many students will participate this year.
