The ratio of the number of red stickers to green stickers is 4 : 3.
After Adam gives away 17 red stickers and gives away 33 green 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 |
12 u |
4 u |
3 u |
21 u |
Change |
- 51 |
- 17 |
- 33 |
- 231 |
After |
21 p |
7 p |
3 p |
21 p |
4 u - 17 = 7 p --- (1)
3 u - 33 = 3 p --- (2)
Make p the same.
(1) x 3
12 u - 51 = 21 p --- (3)
(2) x 7
21 u - 231 = 21 p --- (4)
(4) = (3)
21 u - 231 = 12 u - 51
21 u - 12 u = 231 - 51
9 u = 180
1 u = 180 ÷ 9 = 20
Number of stickers that Adam has now
= 4 u - 17 + 3 u - 33
= 7 u - 50
= 7 x 20 - 50
= 140 - 50
= 90
Answer(s): 90