The ratio of the number of red stickers to blue stickers is 5 : 2.
After Adam gives away 30 red stickers and gives away 100 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 9 : 2.
How many stickers does Adam have now?
|
Make p the same (1) x 2 = (3) |
(1) Red |
(2) Blue |
Make p the same (2) x 9 = (4) |
Before |
10 u |
5 u |
2 u |
18 u |
Change |
- 60 |
- 30 |
- 100 |
- 900 |
After |
18 p |
9 p |
2 p |
18 p |
5 u - 30 = 9 p --- (1)
2 u - 100 = 2 p --- (2)
Make p the same.
(1) x 2
10 u - 60 = 18 p --- (3)
(2) x 9
18 u - 900 = 18 p --- (4)
(4) = (3)
18 u - 900 = 10 u - 60
18 u - 10 u = 900 - 60
8 u = 840
1 u = 840 ÷ 8 = 105
Number of stickers that Adam has now
= 5 u - 30 + 2 u - 100
= 7 u - 130
= 7 x 105 - 130
= 735 - 130
= 605
Answer(s): 605