Adam has some red stickers and blue stickers.
If 247 red stickers are added, 40% of the stickers will be blue stickers.
If 112 blue stickers are added, 20% of the stickers will be red stickers.
- How many red stickers are there?
- How many blue stickers are there?
|
Scenario 1 |
Scenario 2 |
|
Red |
Blue |
Red |
Blue |
Before |
3 u - 247 |
2 u |
1 p |
4 p - 112 |
Change |
+ 247 |
No change |
No change |
+ 112 |
After |
3 u |
2 u |
1 p |
4 p |
(a)
40% =
40100 =
25 20% =
20100 =
15 Scenario 1 Fraction of the stickers that are red
= 1 -
25 =
35 Number of red stickers at first = 3 u - 247
Number of blue stickers at first = 2 u
Scenario 2 Fraction of the stickers that are blue
= 1 -
15=
45 Number of red stickers at first = 1 p
Number of blue stickers at first = 4 p - 112
3 u - 247 = 1 p --- (1)
2 u = 4 p - 112
2 u + 112 = 4 p --- (2)
(1)
x 4 12 u - 988 = 4 p --- (3)
(3) = (2)
12 u - 988 = 2 u + 112
12 u - 2 u = 988 + 112
10 u = 1100
1 u = 1100 ÷ 10 = 110
Number of red stickers
= 3 u - 247
= 3 x 110 - 247
= 330 - 247
= 83
(b)
Number of blue stickers
= 2 u
= 2 x 110
= 220
Answer(s): (a) 83; (b) 220