Your question is vague. There is not enough information. How many balls are in the box? 15 boxes would cost 109.80 thought.
Answer: There are 20 students and 4 students are not here today.
Step-by-step explanation:
If the number of students = 4
Let the number of students be 'x'.
Fraction of students absent = 
If the number of students = 5
Fraction of students absent = 
And Jen came back,
So, the fraction of student absent is also written as

According to question, it becomes,

Hence, there are 20 students in our school.
And number of students are not here today is 
<h3>I hope it is helpful for you ...</h3>
The area of a circle is pi times the radius squared (A = π r²).
3.25 would be 3 1/4 because,
Step 1: You would rewrite the decimal number as a fraction with 1 in the denominator. So, 3.25 = 3.24/1
Step 2: Multiply it by 1 to eliminate 2 decimals places, so multiply the top and bottom by 10^2 = 100
3.25/1 x 100/100 = 325/100
Step 3: Now you find the greatest common factor, also known as GCF, of 325 and 100 if it exits then you reduce the fraction by dividing both numerator and denominator by it. GCF = 25
3.25/100 divided by 25/25 = 13/4
Now you would simplify it to make a proper fraction getting your answer
3 1/4
Does that make sense?