The ratio of the number of red stickers to green stickers is 4 : 1.
After Adam buys another 20 green stickers and gives away 18 red stickers,
the ratio becomes of the number of red stickers to green stickers is 9 : 4.
How many stickers does Adam have now?
|
Make p the same (1) x 4 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 9 = (4) |
Before |
16 u |
4 u |
1 u |
9 u |
Change |
- 72 |
- 18 |
+ 20 |
+ 180 |
After |
36 p |
9 p |
4 p |
36 p |
4 u + 20 = 9 p --- (1)
1 u - 18 = 4 p --- (2)
Make p the same.
(1)
x 416 u - 72 = 36 p --- (3)
(2)
x 99 u + 180 = 36 p --- (4)
(3) = (4)
16 u - 72 = 9 u + 180
16 u - 9 u = 72 + 180
7 u = 252
1 u = 252 ÷ 7 = 36
Number of stickers that Adam have now
= 4 u + 20 + 1 u - 18
= 4 u + 1 u + 20 - 18
= 5 u + 2
= 5 x 36 + 2
= 180 + 2
= 182
Answer(s): 182