PSLE
Gem bought some chocolate bars and gave half of it to Reggie. Reggie bought some jelly beans and gave half of it to Gem. Gem ate 6 jelly beans and Reggie ate 28 chocolate bars. The ratio of Gem's jelly beans to chocolate bars became 1 : 6 and the ratio of Reggie's jelly beans to chocolate bars became 1 : 2. How many chocolate bars did Gem buy?

	Gem		Reggie
	Jelly beans	Chocolate bars	Jelly beans	Chocolate bars
Before	1 u + 6	6 u	1 p	2 p + 28
Change	- 6			- 28
After	1 u	6 u	1 p	2 p

After Gem gave half of the chocolate bars to Reggie and Reggie gave half of his jelly beans to Gem, Reggie and Gem had same number of jelly beans and chocolate bars before each ate some.

6 u = 2 p + 28 
6 u - 28 = 2 p --- (1)

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

Make p the same.

(2)_x2
2 u + 12 = 2 p --- (3)

(1) = (3)
6 u - 28 = 2 u + 12 
6 u - 2 u = 12 + 28
4 u = 40

1 u = 40 ÷ 4 = 10

Number of chocolate bars that Gem bought
= 2 x 6 u
= 12 u
= 12 x 10
= 120

Answer(s): 120