Adam has some red stickers and blue stickers.
If 171 red stickers are added, 30% of the stickers will be blue stickers.
If 391 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 |
7 u - 171 |
3 u |
1 p |
4 p - 391 |
Change |
+ 171 |
No change |
No change |
+ 391 |
After |
7 u |
3 u |
1 p |
4 p |
(a)
30% =
30100 =
310 20% =
20100 =
15 Scenario 1 Fraction of the stickers that are red
= 1 -
310 =
710 Number of red stickers at first = 7 u - 171
Number of blue stickers at first = 3 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 - 391
7 u - 171 = 1 p --- (1)
3 u = 4 p - 391
3 u + 391 = 4 p --- (2)
(1)
x 4 28 u - 684 = 4 p --- (3)
(3) = (2)
28 u - 684 = 3 u + 391
28 u - 3 u = 684 + 391
25 u = 1075
1 u = 1075 ÷ 25 = 43
Number of red stickers
= 7 u - 171
= 7 x 43 - 171
= 301 - 171
= 130
(b)
Number of blue stickers
= 3 u
= 3 x 43
= 129
Answer(s): (a) 130; (b) 129