Class P, Q and R were given some mochi balls to sell for their donation drive. The average number of mochi balls the 3 classes had at first was 239. After Class Q sold four times as many mochi balls as Class P and Class R sold ²₃ as many mochi balls as Class Q, the average number of mochi balls the 3 classes had left was 55. How many mochi balls did Class P and Class R sell altogether?

Class P	Class Q	Class R
1x3	4x3
	3x4	2x4
3 u	12 u	8 u

Class P : Class Q : Class R
3 : 12 : 8

Total number of mochi balls that the 3 classes had at first
= 3 x 239
= 717

Number of mochi balls that the 3 classes left
= 3 x 55 
= 165

Number of mochi balls that were sold by 3 classes
= 717 - 165
= 552

3 u + 12 u + 8 u = 552
23 u = 552

1 u = 552 ÷ 23 = 24

Total number of mochi balls sold by Class P and Class R
= 3 u + 8 u
= 11 u
= 11 x 24
= 264

Answer(s): 264