The ratio of the number of red stickers to green stickers is 3 : 1.
After Adam buys another 29 green stickers and gives away 11 red stickers,
the ratio becomes of the number of red stickers to green stickers is 7 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 7 = (4) |
Before |
9 u |
3 u |
1 u |
7 u |
Change |
- 33 |
- 11 |
+ 29 |
+ 203 |
After |
21 p |
7 p |
3 p |
21 p |
3 u + 29 = 7 p --- (1)
1 u - 11 = 3 p --- (2)
Make p the same.
(1)
x 39 u - 33 = 21 p --- (3)
(2)
x 77 u + 203 = 21 p --- (4)
(3) = (4)
9 u - 33 = 7 u + 203
9 u - 7 u = 33 + 203
2 u = 236
1 u = 236 ÷ 2 = 118
Number of stickers that Adam have now
= 3 u + 29 + 1 u - 11
= 3 u + 1 u + 29 - 11
= 4 u + 18
= 4 x 118 + 18
= 472 + 18
= 490
Answer(s): 490