Question 2
There are eleven boxes, where five are green, five are red and one is blue. Each of these boxes contains exactly 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 and 25 balls, in some order. It is known the total number of balls inside the green boxes is 30 more than the total number of balls inside the red boxes. What is the number of balls inside the blue box?