The ratio of the number of green stickers to red stickers is 5 : 2.
After Adam buys another 30 red stickers and gives away 10 green stickers,
the ratio becomes of the number of green stickers to red stickers is 5 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Green |
(2) Red |
Make p the same (2) x 5 = (4) |
Before |
15 u |
5 u |
2 u |
10 u |
Change |
- 30 |
- 10 |
+ 30 |
+ 150 |
After |
15 p |
5 p |
3 p |
15 p |
5 u + 30 = 5 p --- (1)
2 u - 10 = 3 p --- (2)
Make p the same.
(1)
x 315 u - 30 = 15 p --- (3)
(2)
x 510 u + 150 = 15 p --- (4)
(3) = (4)
15 u - 30 = 10 u + 150
15 u - 10 u = 30 + 150
5 u = 180
1 u = 180 ÷ 5 = 36
Number of stickers that Adam have now
= 5 u + 30 + 2 u - 10
= 5 u + 2 u + 30 - 10
= 7 u + 20
= 7 x 36 + 20
= 252 + 20
= 272
Answer(s): 272