Adam has 700 red and blue stickers.
He buys 20 red stickers and the number of red stickers becomes 2 times as many as blue stickers.
- How many more red stickers than blue stickers does Adam have at first?
- How many less blue stickers than red stickers does Adam have in the end?
|
Red |
Blue |
Before |
2 u - 20 |
1 u |
Change |
+ 20 |
No change |
After |
2 u |
1 u |
(a)
The number of blue stickers remain unchanged.
Total number of stickers at first
= 1 u + 2 u - 20
= 3 u - 20
3 u - 20 = 700
3 u = 700 + 20
3 u = 720
1 u = 720 ÷ 3 = 240
Number of more red stickers than blue stickers at first
= (2 u - 20) - 1 u
= 2 u - 1 u - 20
= 1 u - 20
= 1 x 240 - 20
= 240 - 20
= 220
(b)
Number of less blue stickers than red stickers in the end
= 2 u - 1 u
= 1 u
= 1 x 240
= 240
Answer(s): (a) 220; (b) 240