PSLE
Wendy bought some candy canes and gave half of it to Sean. Sean bought some jelly beans and gave half of it to Wendy. Wendy ate 2 jelly beans and Sean ate 18 candy canes. The ratio of Wendy's jelly beans to candy canes became 1 : 6 and the ratio of Sean's jelly beans to candy canes became 1 : 3. How many jelly beans did Sean buy?

	Wendy		Sean
	Jelly beans	Candy canes	Jelly beans	Candy canes
Before	1 u + 2	6 u	1 p	3 p + 18
Change	- 2			- 18
After	1 u	6 u	1 p	3 p

After Wendy gave half of the candy canes to Sean and Sean gave half of his jelly beans to Wendy, Sean and Wendy had same number of jelly beans and candy canes before each ate some.

6 u = 3 p + 18 
6 u - 18 = 3 p --- (1)

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

Make p the same.

(2)_x3
3 u + 6 = 3 p --- (3)

(1) = (3)
6 u - 18 = 3 u + 6 
6 u - 3 u = 6 + 18
3 u = 24

1 u = 24 ÷ 3 = 8

1 p
= 1 u + 2
= 8 + 2
= 10

Number of jelly beans that Sean bought
= 2 p
= 2 x 10
= 20

Answer(s): 20