The ratio of the number of red stickers to green stickers is 7 : 2.
After Adam gives away 40 red stickers and gives away 72 green stickers,
the ratio becomes of the number of red stickers to green stickers is 9 : 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 9 = (4) |
Before |
14 u |
7 u |
2 u |
18 u |
Change |
- 80 |
- 40 |
- 72 |
- 648 |
After |
18 p |
9 p |
2 p |
18 p |
7 u - 40 = 9 p --- (1)
2 u - 72 = 2 p --- (2)
Make p the same.
(1) x 2
14 u - 80 = 18 p --- (3)
(2) x 9
18 u - 648 = 18 p --- (4)
(4) = (3)
18 u - 648 = 14 u - 80
18 u - 14 u = 648 - 80
4 u = 568
1 u = 568 ÷ 4 = 142
Number of stickers that Adam has now
= 7 u - 40 + 2 u - 72
= 9 u - 112
= 9 x 142 - 112
= 1278 - 112
= 1166
Answer(s): 1166