PSLE
Kimberly bought some candy canes and gave half of it to Vincent. Vincent bought some chocolate bars and gave half of it to Kimberly. Kimberly ate 2 chocolate bars and Vincent ate 20 candy canes. The ratio of Kimberly's chocolate bars to candy canes became 1 : 4 and the ratio of Vincent's chocolate bars to candy canes became 1 : 2. How many chocolate bars did Vincent buy?

	Kimberly		Vincent
	Chocolate bars	Candy canes	Chocolate bars	Candy canes
Before	1 u + 2	4 u	1 p	2 p + 20
Change	- 2			- 20
After	1 u	4 u	1 p	2 p

After Kimberly gave half of the candy canes to Vincent and Vincent gave half of his chocolate bars to Kimberly, Vincent and Kimberly had same number of chocolate bars and candy canes before each ate some.

4 u = 2 p + 20 
4 u - 20 = 2 p --- (1)

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

Make p the same.

(2)_x2
2 u + 4 = 2 p --- (3)

(1) = (3)
4 u - 20 = 2 u + 4 
4 u - 2 u = 4 + 20
2 u = 24

1 u = 24 ÷ 2 = 12

1 p
= 1 u + 2
= 12 + 2
= 14

Number of chocolate bars that Vincent bought
= 2 p
= 2 x 14
= 28

Answer(s): 28