Adam has 500 red and green stickers.
He buys 20 red stickers and the number of red stickers becomes 3 times as many as green stickers.
- How many more red stickers than green stickers does Adam have at first?
- How many less green stickers than red stickers does Adam have in the end?
|
Red |
Green |
Before |
3 u - 20 |
1 u |
Change |
+ 20 |
No change |
After |
3 u |
1 u |
(a)
The number of green stickers remain unchanged.
Total number of stickers at first
= 1 u + 3 u - 20
= 4 u - 20
4 u - 20 = 500
4 u = 500 + 20
4 u = 520
1 u = 520 ÷ 4 = 130
Number of more red stickers than green stickers at first
= (3 u - 20) - 1 u
= 3 u - 1 u - 20
= 2 u - 20
= 2 x 130 - 20
= 260 - 20
= 240
(b)
Number of less green stickers than red stickers in the end
= 3 u - 1 u
= 2 u
= 2 x 130
= 260
Answer(s): (a) 240; (b) 260