At first, Henry, Zoe and Oliver had some chocolate bars in the ratio 6 : 4 : 5 respectively. Henry had 360 chocolate bars. Then he gave all his chocolate bars to Zoe and Oliver. After receiving the chocolate bars from Henry, Zoe and Oliver had the same number of chocolate bars. How many chocolate bars did Zoe receive from Henry?

	Henry	Zoe	Oliver	Total
Before	6x2 = 12 u	4x2 = 8 u	5x2 = 10 u	15x2 = 30 u
Change	- 6 u	+ 6 u
After	0	1x15 = 15 u	1x15 = 15 u	2x15 = 30 u

The total number of chocolate bars remains unchanged. Make the total number of chocolate bars the same.  LCM of 2 and 15 is 30.

Total number of chocolate bars = 30 u

Number of chocolate bars that Zoe had in the end 
= 30 u ÷ 2
= 15 u

Number of chocolate bars that Henry had at first = 6 u 

6 u = 360

1 u = 360 ÷ 6 = 60

Number of chocolate bars that Zoe received from Henry
= 15 u - 8 u
= 7 u
= 7 x 60
= 420

Answer(s): 420