The ratio of the number of green stickers to blue stickers is 4 : 1.
After Adam buys another 20 green stickers and 90 blue stickers,
the ratio becomes of the number of green stickers to blue stickers is 7 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Green |
(2) Blue |
Make p the same (2) x 7 = (4) |
Before |
12 u |
4 u |
1 u |
7 u |
Change |
+ 60 |
+ 20 |
+ 90 |
+ 630 |
After |
12 u + 60 |
4 u + 20 |
1 u + 90 |
7 u + 630 |
Comparing the green stickers and the blue stickers in the end |
21 p |
7 p |
3 p |
21 p |
4 u + 20 = 7 p --- (1)
1 u + 90 = 3 p --- (2)
Make p the same by using the LCM of 3 and 7.
LCM of 3 and 7 is 21.
(1)
x 3 12 u + 60 = 21 p --- (3)
(2)
x 7 7 u + 630 = 21 p --- (4)
(3) = (4)
12 u + 60 = 7 u + 630
12 u - 7 u = 630 - 60
5 u = 570
1 u = 570 ÷ 5 = 114
Number of stickers that Adam has now
= 4 u + 20 + 1 u + 90
= 4 u + 1 u + 20 + 90
= 5 u + 110
= 5 x 114 + 110
= 570 + 110
= 680
Answer(s): 680