Adam has some blue stickers and red stickers.
If 20 blue stickers are added, 80% of the stickers will be red stickers.
If 320 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 |
3 u - 20 |
12 u |
28 u - 320 |
12 u |
Change |
+ 20 |
No change |
+ 320 |
No change |
After |
1x3 = 3 u |
4x3 = 12 u |
7x4 = 28 u |
3x4 = 12 u |
(a)
80% =
80100 =
4530% =
30100 =
310 Scenario 1 Fraction of the stickers that are blue in the end
= 1 -
45 =
15 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 4 and 3 = 12
28 u - 320 = 3 u - 20
28 u - 3 u = 320 - 20
25 u = 300
1 u = 300 ÷ 25 = 12
Number of blue stickers
= 3 u - 20
= 3 x 12 - 20
= 36 - 20
= 16
(b)
Number of red stickers
= 12 u
= 12 x 12
= 144
Answer(s): (a) 16; (b) 144