Mrs Ng had a total of 99 white and pink daisies in the ratio of 7 : 4. After she had given away 3 times as many white daisies as pink daisies, the number of white and pink daisies left was in the ratio of 6 : 5. How many more white daisies than pink daisies did she give away?
|
White |
Pink |
Total |
Before |
7 b |
4 b |
11 b |
Change |
- 3 u |
- 1 u |
|
After |
6 p |
5 p |
|
|
Make p the same (1)x5 = (3) |
White (1) |
Pink (2) |
Make p the same (2)x6 = (4) |
Before |
315 |
63 |
36 |
216 |
Change |
- 15 u |
- 3 u |
- 1 u |
- 6 u |
After |
30 p |
6 p |
5 p |
30 p |
Number of daisies at first
= 7 b + 4 b
= 11 b
11 b = 99
1 b = 99 ÷ 11 = 9
Number of white daisies at first
= 7 b
= 7 x 9
= 63
Number of pink daisies at first
= 4 b
= 4 x 9
= 36
63 - 3 u = 6 p --- (1)
36 - 1 u = 5 p --- (2)
Make p the same.
(1)
x5 315 - 15 u =
30 p --- (3)
(2)
x6 = (4)
216 - 6 u =
30 p --- (4)
(3) = (4)
315 - 15 u = 216 - 6 u
15 u - 6 u = 315 - 216
9 u = 99
1 u = 99 ÷ 9 = 11
Number of more white daisies than pink daisies that she gave away
= 3 u - 1 u
= 2 u
= 2 x 11
= 22
Answer(s): 22