Adam has 100 green and red stickers.
He buys 20 green stickers and the number of green stickers becomes 2 times as many as red stickers.
- How many more green stickers than red stickers does Adam have at first?
- How many less red stickers than green stickers does Adam have in the end?
|
Green |
Red |
Before |
2 u - 20 |
1 u |
Change |
+ 20 |
No change |
After |
2 u |
1 u |
(a)
The number of red stickers remain unchanged.
Total number of stickers at first
= 1 u + 2 u - 20
= 3 u - 20
3 u - 20 = 100
3 u = 100 + 20
3 u = 120
1 u = 120 ÷ 3 = 40
Number of more green stickers than red stickers at first
= (2 u - 20) - 1 u
= 2 u - 1 u - 20
= 1 u - 20
= 1 x 40 - 20
= 40 - 20
= 20
(b)
Number of less red stickers than green stickers in the end
= 2 u - 1 u
= 1 u
= 1 x 40
= 40
Answer(s): (a) 20; (b) 40