The ratio of the number of blue stickers to red stickers is 3 : 2.
After Adam gives away 18 blue stickers and gives away 78 red stickers,
the ratio becomes of the number of blue stickers to red stickers is 7 : 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 7 = (4) |
Before |
12 u |
3 u |
2 u |
14 u |
Change |
- 72 |
- 18 |
- 78 |
- 546 |
After |
28 p |
7 p |
4 p |
28 p |
3 u - 18 = 7 p --- (1)
2 u - 78 = 4 p --- (2)
Make p the same.
(1) x 4
12 u - 72 = 28 p --- (3)
(2) x 7
14 u - 546 = 28 p --- (4)
(4) = (3)
14 u - 546 = 12 u - 72
14 u - 12 u = 546 - 72
2 u = 474
1 u = 474 ÷ 2 = 237
Number of stickers that Adam has now
= 3 u - 18 + 2 u - 78
= 5 u - 96
= 5 x 237 - 96
= 1185 - 96
= 1089
Answer(s): 1089