The ratio of the number of blue stickers to red stickers is 5 : 2.
After Adam buys another 16 red stickers and gives away 15 blue stickers,
the ratio becomes of the number of blue stickers to red stickers is 9 : 4.
How many stickers does Adam have now?
|
Make p the same (1) x 4 = (3) |
(1) Blue |
(2) Red |
Make p the same (2) x 9 = (4) |
Before |
20 u |
5 u |
2 u |
18 u |
Change |
- 60 |
- 15 |
+ 16 |
+ 144 |
After |
36 p |
9 p |
4 p |
36 p |
5 u + 16 = 9 p --- (1)
2 u - 15 = 4 p --- (2)
Make p the same.
(1)
x 420 u - 60 = 36 p --- (3)
(2)
x 918 u + 144 = 36 p --- (4)
(3) = (4)
20 u - 60 = 18 u + 144
20 u - 18 u = 60 + 144
2 u = 204
1 u = 204 ÷ 2 = 102
Number of stickers that Adam have now
= 5 u + 16 + 2 u - 15
= 5 u + 2 u + 16 - 15
= 7 u + 1
= 7 x 102 + 1
= 714 + 1
= 715
Answer(s): 715