PSLE
Wendy bought some jelly beans and gave half of it to Billy. Billy bought some sweets and gave half of it to Wendy. Wendy ate 2 sweets and Billy ate 27 jelly beans. The ratio of Wendy's sweets to jelly beans became 1 : 6 and the ratio of Billy's sweets to jelly beans became 1 : 3. How many jelly beans did Wendy buy?

	Wendy		Billy
	Sweets	Jelly beans	Sweets	Jelly beans
Before	1 u + 2	6 u	1 p	3 p + 27
Change	- 2			- 27
After	1 u	6 u	1 p	3 p

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

6 u = 3 p + 27 
6 u - 27 = 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 - 27 = 3 u + 6 
6 u - 3 u = 6 + 27
3 u = 33

1 u = 33 ÷ 3 = 11

Number of jelly beans that Wendy bought
= 2 x 6 u
= 12 u
= 12 x 11
= 132

Answer(s): 132