Adam has some blue stickers and red stickers.
If 163 blue stickers are removed, 70% of the stickers will be red stickers.
If 117 blue stickers are added, 30% of the stickers will be red stickers.
- How many blue stickers are there?
- How many red stickers are there?
|
Scenario 1 |
Scenario 2 |
|
Blue |
Red |
Blue |
Red |
Before |
9 u + 163 |
21 u |
49 u - 117 |
21 u |
Change |
- 163 |
No change |
+ 117 |
No change |
After |
3x3 = 9 u |
7x3 = 21 u |
7x7 = 49 u |
3x7 = 21 u |
(a)
70% =
70100 =
71030% =
30100 =
310Scenario 1 Fraction of the stickers that are blue in the end
= 1 -
710 =
310 Scenario 2
Fraction of the stickers that are blue in the end
= 1 -
310 =
710 The number of red stickers remains unchanged in both scenarios.
LCM of 7 and 3 = 21
49 u - 117 = 9 u + 163
49 u - 9 u = 163 + 117
40 u = 280
1 u = 280 ÷ 40 = 7
Number of blue stickers
= 9 u + 163
= 9 x 7 + 163
= 63 + 163
= 226
(b)
Number of red stickers
= 21 u
= 21 x 7
= 147
Answer(s): (a) 226; (b) 147