Adam has 90 stickers.
After
37 of the blue stickers is given away and
another 20 red stickers are bought,
there is an equal number of blue and red stickers.
- How many blue stickers are there in the end?
- How many less red stickers than blue stickers are there at first?
- How many blue stickers are given away?
|
Blue |
Red |
Before |
7 u |
4 u - 20 |
Change |
- 3 u |
+ 20 |
After |
4 u |
4 u |
(a)
Fraction of the blue stickers left
= 1 -
37 =
47 The number of blue stickers and red stickers in the end is the same.
Total number of stickers at first
= 7 u + 4 u - 20
= 11 u - 20
11 u - 20 = 90
11 u = 90 + 20
11 u = 110
1 u = 110 ÷ 11 = 10
Number of blue stickers in the end
= 4 u
= 4 x 10
= 40
(b)
Number of less red stickers than blue stickers at first
= 7 u - (4 u - 20)
= 7 u - 4 u + 20
= 3 u + 20
= 3 x 10 + 20
= 30 + 20
= 50
(c)
Number of blue stickers given away
= 3 u
= 3 x 10
= 30
Answer(s): (a) 40; (b) 50; (c) 30