The ratio of the number of red stickers to green stickers is 7 : 3.
After Adam gives away 42 red stickers and gives away 100 green stickers,
the ratio becomes of the number of red stickers to green stickers is 7 : 2.
How many stickers does Adam have now?
|
Make p the same (1) x 2 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 7 = (4) |
Before |
14 u |
7 u |
3 u |
21 u |
Change |
- 84 |
- 42 |
- 100 |
- 700 |
After |
14 p |
7 p |
2 p |
14 p |
7 u - 42 = 7 p --- (1)
3 u - 100 = 2 p --- (2)
Make p the same.
(1) x 2
14 u - 84 = 14 p --- (3)
(2) x 7
21 u - 700 = 14 p --- (4)
(4) = (3)
21 u - 700 = 14 u - 84
21 u - 14 u = 700 - 84
7 u = 616
1 u = 616 ÷ 7 = 88
Number of stickers that Adam has now
= 7 u - 42 + 3 u - 100
= 10 u - 142
= 10 x 88 - 142
= 880 - 142
= 738
Answer(s): 738