Class C, D and E were given some sweets to sell for their charity drive. The average number of sweets the 3 classes had at first was 204. After Class D sold twice as many sweets as Class C and Class E sold ³₄ as many sweets as Class D, the average number of sweets the 3 classes had left was 42. How many sweets did Class C and Class E sell altogether?

Class C	Class D	Class E
1x2	2x2
	4x1	3x1
2 u	4 u	3 u

Class C : Class D : Class E
2 : 4 : 3

Total number of sweets that the 3 classes had at first
= 3 x 204
= 612

Number of sweets that the 3 classes left
= 3 x 42 
= 126

Number of sweets that were sold by 3 classes
= 612 - 126
= 486

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

1 u = 486 ÷ 9 = 54

Total number of sweets sold by Class C and Class E
= 2 u + 3 u
= 5 u
= 5 x 54
= 270

Answer(s): 270