PSLE
Ivory bought some lollipops and gave half of it to Perry. Perry bought some sweets and gave half of it to Ivory. Ivory ate 2 sweets and Perry ate 18 lollipops. The ratio of Ivory's sweets to lollipops became 1 : 4 and the ratio of Perry's sweets to lollipops became 1 : 2. How many lollipops did Ivory buy?

	Ivory		Perry
	Sweets	Lollipops	Sweets	Lollipops
Before	1 u + 2	4 u	1 p	2 p + 18
Change	- 2			- 18
After	1 u	4 u	1 p	2 p

After Ivory gave half of the lollipops to Perry and Perry gave half of his sweets to Ivory, Perry and Ivory had same number of sweets and lollipops before each ate some.

4 u = 2 p + 18 
4 u - 18 = 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 - 18 = 2 u + 4 
4 u - 2 u = 4 + 18
2 u = 22

1 u = 22 ÷ 2 = 11

Number of lollipops that Ivory bought
= 2 x 4 u
= 8 u
= 8 x 11
= 88

Answer(s): 88