The ratio of the number of blue stickers to green stickers is 5 : 2.
After Adam gives away 40 blue stickers and gives away 80 green stickers,
the ratio becomes of the number of blue stickers to green stickers is 9 : 2.
How many stickers does Adam have now?
|
Make p the same (1) x 2 = (3) |
(1) Blue |
(2) Green |
Make p the same (2) x 9 = (4) |
Before |
10 u |
5 u |
2 u |
18 u |
Change |
- 80 |
- 40 |
- 80 |
- 720 |
After |
18 p |
9 p |
2 p |
18 p |
5 u - 40 = 9 p --- (1)
2 u - 80 = 2 p --- (2)
Make p the same.
(1) x 2
10 u - 80 = 18 p --- (3)
(2) x 9
18 u - 720 = 18 p --- (4)
(4) = (3)
18 u - 720 = 10 u - 80
18 u - 10 u = 720 - 80
8 u = 640
1 u = 640 ÷ 8 = 80
Number of stickers that Adam has now
= 5 u - 40 + 2 u - 80
= 7 u - 120
= 7 x 80 - 120
= 560 - 120
= 440
Answer(s): 440