Adam has 900 red and blue stickers.
He buys 90 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 - 90 |
1 u |
Change |
+ 90 |
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 - 90
= 3 u - 90
3 u - 90 = 900
3 u = 900 + 90
3 u = 990
1 u = 990 ÷ 3 = 330
Number of more red stickers than blue stickers at first
= (2 u - 90) - 1 u
= 2 u - 1 u - 90
= 1 u - 90
= 1 x 330 - 90
= 330 - 90
= 240
(b)
Number of less blue stickers than red stickers in the end
= 2 u - 1 u
= 1 u
= 1 x 330
= 330
Answer(s): (a) 240; (b) 330