PSLE
Sabrina bought some jelly beans and gave half of it to Will. Will bought some chocolate bars and gave half of it to Sabrina. Sabrina ate 4 chocolate bars and Will ate 40 jelly beans. The ratio of Sabrina's chocolate bars to jelly beans became 1 : 5 and the ratio of Will's chocolate bars to jelly beans became 1 : 2. How many jelly beans did Sabrina buy?

	Sabrina		Will
	Chocolate bars	Jelly beans	Chocolate bars	Jelly beans
Before	1 u + 4	5 u	1 p	2 p + 40
Change	- 4			- 40
After	1 u	5 u	1 p	2 p

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

5 u = 2 p + 40 
5 u - 40 = 2 p --- (1)

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

Make p the same.

(2)_x2
2 u + 8 = 2 p --- (3)

(1) = (3)
5 u - 40 = 2 u + 8 
5 u - 2 u = 8 + 40
3 u = 48

1 u = 48 ÷ 3 = 16

Number of jelly beans that Sabrina bought
= 2 x 5 u
= 10 u
= 10 x 16
= 160

Answer(s): 160