The ratio of the number of red stickers to green stickers is 7 : 4.
After Adam buys another 10 red stickers and 80 green stickers,
the ratio becomes of the number of red stickers to green stickers is 4 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 4 = (4) |
Before |
21 u |
7 u |
4 u |
16 u |
Change |
+ 30 |
+ 10 |
+ 80 |
+ 320 |
After |
21 u + 30 |
7 u + 10 |
4 u + 80 |
16 u + 320 |
Comparing the red stickers and the green stickers in the end |
12 p |
4 p |
3 p |
12 p |
7 u + 10 = 4 p --- (1)
4 u + 80 = 3 p --- (2)
Make p the same by using the LCM of 3 and 4.
LCM of 3 and 4 is 12.
(1)
x 3 21 u + 30 = 12 p --- (3)
(2)
x 4 16 u + 320 = 12 p --- (4)
(3) = (4)
21 u + 30 = 16 u + 320
21 u - 16 u = 320 - 30
5 u = 290
1 u = 290 ÷ 5 = 58
Number of stickers that Adam has now
= 7 u + 10 + 4 u + 80
= 7 u + 4 u + 10 + 80
= 11 u + 90
= 11 x 58 + 90
= 638 + 90
= 728
Answer(s): 728