Adam has 108 stickers.
After
35 of the red stickers is given away and
another 39 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 |
2 u - 39 |
Change |
- 3 u |
+ 39 |
After |
2 u |
2 u |
(a)
Fraction of the red stickers left
= 1 -
35 =
25 The number of red stickers and blue stickers in the end is the same.
Total number of stickers at first
= 5 u + 2 u - 39
= 7 u - 39
7 u - 39 = 108
7 u = 108 + 39
7 u = 147
1 u = 147 ÷ 7 = 21
Number of red stickers in the end
= 2 u
= 2 x 21
= 42
(b)
Number of less blue stickers than red stickers at first
= 5 u - (2 u - 39)
= 5 u - 2 u + 39
= 3 u + 39
= 3 x 21 + 39
= 63 + 39
= 102
(c)
Number of red stickers given away
= 3 u
= 3 x 21
= 63
Answer(s): (a) 42; (b) 102; (c) 63