Adam has 89 stickers.
After
47 of the red stickers is given away and
another 21 blue stickers are bought,
there is an equal number of red and blue stickers.
- How many red stickers are there in the end?
- How many less blue stickers than red stickers are there at first?
- How many red stickers are given away?
|
Red |
Blue |
Before |
7 u |
3 u - 21 |
Change |
- 4 u |
+ 21 |
After |
3 u |
3 u |
(a)
Fraction of the red stickers left
= 1 -
47 =
37 The number of red stickers and blue stickers in the end is the same.
Total number of stickers at first
= 7 u + 3 u - 21
= 10 u - 21
10 u - 21 = 89
10 u = 89 + 21
10 u = 110
1 u = 110 ÷ 10 = 11
Number of red stickers in the end
= 3 u
= 3 x 11
= 33
(b)
Number of less blue stickers than red stickers at first
= 7 u - (3 u - 21)
= 7 u - 3 u + 21
= 4 u + 21
= 4 x 11 + 21
= 44 + 21
= 65
(c)
Number of red stickers given away
= 4 u
= 4 x 11
= 44
Answer(s): (a) 33; (b) 65; (c) 44