Mrs Lin had a total of 117 pink and white lilies in the ratio of 10 : 3. After she had given away 5 times as many pink lilies as white lilies, the number of pink and white lilies left was in the ratio of 5 : 4. How many more pink lilies than white lilies did she give away?

	Pink	White	Total
Before	10 b	3 b	13 b
Change	- 5 u	- 1 u
After	5 p	4 p

	Make p the same (1)x4 = (3)	Pink (1)	White (2)	Make p the same (2)x5 = (4)
Before	360	90	27	135
Change	- 20 u	- 5 u	- 1 u	- 5 u
After	20 p	5 p	4 p	20 p

Number of lilies at first
= 10 b + 3 b
= 13 b

13 b = 117

1 b = 117 ÷ 13 = 9

Number of pink lilies at first
= 10 b
= 10 x 9
= 90

Number of white lilies at first
= 3 b
= 3 x 9
= 27

90 - 5 u = 5 p --- (1)

27 - 1 u = 4 p --- (2)

Make p the same.

(1)_x4 
360 - 20 u = 20 p --- (3)

(2)_x5 = (4)
135 - 5 u = 20 p --- (4)

(3) = (4)
360 - 20 u = 135 - 5 u
20 u - 5 u = 360 - 135
15 u = 225

1 u = 225 ÷ 15 = 15

Number of more pink lilies than white lilies that she gave away
= 5 u - 1 u
= 4 u
= 4 x 15
= 60

Answer(s): 60