The ratio of the number of red stickers to blue stickers is 4 : 3.
After Adam gives away 45 red stickers and gives away 78 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 5 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Red |
(2) Blue |
Make p the same (2) x 5 = (4) |
Before |
12 u |
4 u |
3 u |
15 u |
Change |
- 135 |
- 45 |
- 78 |
- 390 |
After |
15 p |
5 p |
3 p |
15 p |
4 u - 45 = 5 p --- (1)
3 u - 78 = 3 p --- (2)
Make p the same.
(1) x 3
12 u - 135 = 15 p --- (3)
(2) x 5
15 u - 390 = 15 p --- (4)
(4) = (3)
15 u - 390 = 12 u - 135
15 u - 12 u = 390 - 135
3 u = 255
1 u = 255 ÷ 3 = 85
Number of stickers that Adam has now
= 4 u - 45 + 3 u - 78
= 7 u - 123
= 7 x 85 - 123
= 595 - 123
= 472
Answer(s): 472