Adam has some blue stickers and red stickers.
If 225 blue stickers are added, 30% of the stickers will be red stickers.
If 300 red stickers are added, 20% of the stickers will be blue stickers.
- How many blue stickers are there?
- How many red stickers are there?
|
Scenario 1 |
Scenario 2 |
|
Blue |
Red |
Blue |
Red |
Before |
7 u - 225 |
3 u |
1 p |
4 p - 300 |
Change |
+ 225 |
No change |
No change |
+ 300 |
After |
7 u |
3 u |
1 p |
4 p |
(a)
30% =
30100 =
310 20% =
20100 =
15 Scenario 1 Fraction of the stickers that are blue
= 1 -
310 =
710 Number of blue stickers at first = 7 u - 225
Number of red stickers at first = 3 u
Scenario 2 Fraction of the stickers that are red
= 1 -
15=
45 Number of blue stickers at first = 1 p
Number of red stickers at first = 4 p - 300
7 u - 225 = 1 p --- (1)
3 u = 4 p - 300
3 u + 300 = 4 p --- (2)
(1)
x 4 28 u - 900 = 4 p --- (3)
(3) = (2)
28 u - 900 = 3 u + 300
28 u - 3 u = 900 + 300
25 u = 1200
1 u = 1200 ÷ 25 = 48
Number of blue stickers
= 7 u - 225
= 7 x 48 - 225
= 336 - 225
= 111
(b)
Number of red stickers
= 3 u
= 3 x 48
= 144
Answer(s): (a) 111; (b) 144