Adam has some red stickers and blue stickers.
If 180 red stickers are removed, 20% of the stickers will be red stickers.
If 400 blue stickers are removed, 10% of the stickers will be blue stickers.
- How many red stickers are there?
- How many blue stickers are there?
|
Scenario 1 |
Scenario 2 |
|
Red |
Blue |
Red |
Blue |
Before |
1 u + 180 |
4 u |
9 p |
1 p + 400 |
Change |
- 180 |
No change |
No change |
- 400 |
After |
1 u |
4 u |
9 p |
1 p |
(a)
20% =
20100 =
15 10% =
10100 =
110 Scenario 1Fraction of the stickers that are blue
= 1 -
15 =
45 Scenario 2Fraction of the stickers that are red
= 1 -
110 =
9101 u + 180 = 9 p --- (1)
4 u = 1 p + 400 --- (2)
From (1)
1 u = 9 p - 180 --- (3)
(3)
x 44 u = 36 p - 720 --- (4)
(4) = (2)
36 p - 720 = 1 p + 400
36 p - 1 p = 720 + 400
35 p = 1120
1 p = 1120 ÷ 35 = 32Number of red stickers = 9 p
= 9 x 32= 288 (b) Number of blue stickers = 1 p + 400 = 32 + 400 = 432 Answer(s): (a) 288; (b) 432