Adam has 900 blue and red stickers.
He buys 20 blue stickers and the number of blue stickers becomes 3 times as many as red stickers.
- How many more blue stickers than red stickers does Adam have at first?
- How many less red stickers than blue stickers does Adam have in the end?
|
Blue |
Red |
Before |
3 u - 20 |
1 u |
Change |
+ 20 |
No change |
After |
3 u |
1 u |
(a)
The number of red stickers remain unchanged.
Total number of stickers at first
= 1 u + 3 u - 20
= 4 u - 20
4 u - 20 = 900
4 u = 900 + 20
4 u = 920
1 u = 920 ÷ 4 = 230
Number of more blue stickers than red stickers at first
= (3 u - 20) - 1 u
= 3 u - 1 u - 20
= 2 u - 20
= 2 x 230 - 20
= 460 - 20
= 440
(b)
Number of less red stickers than blue stickers in the end
= 3 u - 1 u
= 2 u
= 2 x 230
= 460
Answer(s): (a) 440; (b) 460