The ratio of the number of green stickers to blue stickers is 3 : 1.
After Adam buys another 30 blue stickers and gives away 10 green stickers,
the ratio becomes of the number of green stickers to blue stickers is 7 : 4.
How many stickers does Adam have now?
|
Make p the same (1) x 4 = (3) |
(1) Green |
(2) Blue |
Make p the same (2) x 7 = (4) |
Before |
12 u |
3 u |
1 u |
7 u |
Change |
- 40 |
- 10 |
+ 30 |
+ 210 |
After |
28 p |
7 p |
4 p |
28 p |
3 u + 30 = 7 p --- (1)
1 u - 10 = 4 p --- (2)
Make p the same.
(1)
x 412 u - 40 = 28 p --- (3)
(2)
x 77 u + 210 = 28 p --- (4)
(3) = (4)
12 u - 40 = 7 u + 210
12 u - 7 u = 40 + 210
5 u = 250
1 u = 250 ÷ 5 = 50
Number of stickers that Adam have now
= 3 u + 30 + 1 u - 10
= 3 u + 1 u + 30 - 10
= 4 u + 20
= 4 x 50 + 20
= 200 + 20
= 220
Answer(s): 220