PSLE
Marion bought some chocolate bars and gave half of it to Simon. Simon bought some sweets and gave half of it to Marion. Marion ate 7 sweets and Simon ate 34 chocolate bars. The ratio of Marion's sweets to chocolate bars became 1 : 6 and the ratio of Simon's sweets to chocolate bars became 1 : 2. How many chocolate bars did Marion buy?

	Marion		Simon
	Sweets	Chocolate bars	Sweets	Chocolate bars
Before	1 u + 7	6 u	1 p	2 p + 34
Change	- 7			- 34
After	1 u	6 u	1 p	2 p

After Marion gave half of the chocolate bars to Simon and Simon gave half of his sweets to Marion, Simon and Marion had same number of sweets and chocolate bars before each ate some.

6 u = 2 p + 34 
6 u - 34 = 2 p --- (1)

1 u + 7 = 1 p --- (2)

Make p the same.

(2)_x2
2 u + 14 = 2 p --- (3)

(1) = (3)
6 u - 34 = 2 u + 14 
6 u - 2 u = 14 + 34
4 u = 48

1 u = 48 ÷ 4 = 12

Number of chocolate bars that Marion bought
= 2 x 6 u
= 12 u
= 12 x 12
= 144

Answer(s): 144