The ratio of the number of blue stickers to green stickers is 3 : 1.
After Adam buys another 33 green stickers and gives away 13 blue stickers,
the ratio becomes of the number of blue stickers to green stickers is 7 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Blue |
(2) Green |
Make p the same (2) x 7 = (4) |
Before |
9 u |
3 u |
1 u |
7 u |
Change |
- 39 |
- 13 |
+ 33 |
+ 231 |
After |
21 p |
7 p |
3 p |
21 p |
3 u + 33 = 7 p --- (1)
1 u - 13 = 3 p --- (2)
Make p the same.
(1)
x 39 u - 39 = 21 p --- (3)
(2)
x 77 u + 231 = 21 p --- (4)
(3) = (4)
9 u - 39 = 7 u + 231
9 u - 7 u = 39 + 231
2 u = 270
1 u = 270 ÷ 2 = 135
Number of stickers that Adam have now
= 3 u + 33 + 1 u - 13
= 3 u + 1 u + 33 - 13
= 4 u + 20
= 4 x 135 + 20
= 540 + 20
= 560
Answer(s): 560