Class H, J and K were given some mochi balls to sell for their fund-raising project. The average number of mochi balls the 3 classes had at first was 209. After Class J sold twice as many mochi balls as Class H and Class K sold ³₄ as many mochi balls as Class J, the average number of mochi balls the 3 classes had left was 47. How many mochi balls did Class H and Class K sell altogether?

Class H	Class J	Class K
1x2	2x2
	4x1	3x1
2 u	4 u	3 u

Class H : Class J : Class K
2 : 4 : 3

Total number of mochi balls that the 3 classes had at first
= 3 x 209
= 627

Number of mochi balls that the 3 classes left
= 3 x 47 
= 141

Number of mochi balls that were sold by 3 classes
= 627 - 141
= 486

2 u + 4 u + 3 u = 486
9 u = 486

1 u = 486 ÷ 9 = 54

Total number of mochi balls sold by Class H and Class K
= 2 u + 3 u
= 5 u
= 5 x 54
= 270

Answer(s): 270