Adam has 21 stickers.
After
29 of the green stickers is given away and
another 11 red stickers are bought,
there is an equal number of green and red stickers.
- How many green stickers are there in the end?
- How many less red stickers than green stickers are there at first?
- How many green stickers are given away?
|
Green |
Red |
Before |
9 u |
7 u - 11 |
Change |
- 2 u |
+ 11 |
After |
7 u |
7 u |
(a)
Fraction of the green stickers left
= 1 -
29 =
79 The number of green stickers and red stickers in the end is the same.
Total number of stickers at first
= 9 u + 7 u - 11
= 16 u - 11
16 u - 11 = 21
16 u = 21 + 11
16 u = 32
1 u = 32 ÷ 16 = 2
Number of green stickers in the end
= 7 u
= 7 x 2
= 14
(b)
Number of less red stickers than green stickers at first
= 9 u - (7 u - 11)
= 9 u - 7 u + 11
= 2 u + 11
= 2 x 2 + 11
= 4 + 11
= 15
(c)
Number of green stickers given away
= 2 u
= 2 x 2
= 4
Answer(s): (a) 14; (b) 15; (c) 4