Adam has 157 stickers.
After
710 of the red stickers is given away and
another 12 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 |
10 u |
3 u - 12 |
Change |
- 7 u |
+ 12 |
After |
3 u |
3 u |
(a)
Fraction of the red stickers left
= 1 -
710 =
310 The number of red stickers and blue stickers in the end is the same.
Total number of stickers at first
= 10 u + 3 u - 12
= 13 u - 12
13 u - 12 = 157
13 u = 157 + 12
13 u = 169
1 u = 169 ÷ 13 = 13
Number of red stickers in the end
= 3 u
= 3 x 13
= 39
(b)
Number of less blue stickers than red stickers at first
= 10 u - (3 u - 12)
= 10 u - 3 u + 12
= 7 u + 12
= 7 x 13 + 12
= 91 + 12
= 103
(c)
Number of red stickers given away
= 7 u
= 7 x 13
= 91
Answer(s): (a) 39; (b) 103; (c) 91