Adam has 33 stickers.
After
25 of the red stickers is given away and
another 7 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 |
5 u |
3 u - 7 |
Change |
- 2 u |
+ 7 |
After |
3 u |
3 u |
(a)
Fraction of the red stickers left
= 1 -
25 =
35 The number of red stickers and blue stickers in the end is the same.
Total number of stickers at first
= 5 u + 3 u - 7
= 8 u - 7
8 u - 7 = 33
8 u = 33 + 7
8 u = 40
1 u = 40 ÷ 8 = 5
Number of red stickers in the end
= 3 u
= 3 x 5
= 15
(b)
Number of less blue stickers than red stickers at first
= 5 u - (3 u - 7)
= 5 u - 3 u + 7
= 2 u + 7
= 2 x 5 + 7
= 10 + 7
= 17
(c)
Number of red stickers given away
= 2 u
= 2 x 5
= 10
Answer(s): (a) 15; (b) 17; (c) 10