Adam has some red stickers and green stickers.
If 380 red stickers are removed, 90% of the stickers will be green stickers.
If 100 red stickers are removed, 20% of the stickers will be green stickers.
- How many red stickers are there?
- How many green stickers are there?
|
Scenario 1 |
Scenario 2 |
|
Red |
Green |
Red |
Green |
Before |
1 u + 380 |
9 u |
36 u + 100 |
9 u |
Change |
- 380 |
No change |
- 100 |
No change |
After |
1x1 = 1 u |
9x1 = 9 u |
4x9 = 36 u |
1x9 = 9 u |
(a)
90% =
90100 =
91020% =
20100 =
15Scenario 1 Fraction of the stickers that are red in the end
= 1 -
910 =
110 Scenario 2
Fraction of the stickers that are red in the end
= 1 -
15 =
45 The number of green stickers remains unchanged in both scenarios.
LCM of 9 and 1 = 9
1 u + 380 = 36 u + 100
36 u - 1 u = 380 - 100
35 u = 280
1 u = 280 ÷ 35 = 8
Number of red stickers
= 1 u + 380
= 1 x 8 + 380
= 8 + 380
= 388
(b)
Number of green stickers
= 9 u
= 9 x 8
= 72
Answer(s): (a) 388; (b) 72