The ratio of the number of red stickers to green stickers is 5 : 2.
After Adam gives away 12 red stickers and gives away 12 green stickers,
the ratio becomes of the number of red stickers to green stickers is 7 : 2.
How many stickers does Adam have now?
|
Make p the same (1) x 2 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 7 = (4) |
Before |
10 u |
5 u |
2 u |
14 u |
Change |
- 24 |
- 12 |
- 12 |
- 84 |
After |
14 p |
7 p |
2 p |
14 p |
5 u - 12 = 7 p --- (1)
2 u - 12 = 2 p --- (2)
Make p the same.
(1) x 2
10 u - 24 = 14 p --- (3)
(2) x 7
14 u - 84 = 14 p --- (4)
(4) = (3)
14 u - 84 = 10 u - 24
14 u - 10 u = 84 - 24
4 u = 60
1 u = 60 ÷ 4 = 15
Number of stickers that Adam has now
= 5 u - 12 + 2 u - 12
= 7 u - 24
= 7 x 15 - 24
= 105 - 24
= 81
Answer(s): 81