The ratio of the number of blue stickers to red stickers is 7 : 3.
After Adam buys another 60 blue stickers and 90 red stickers,
the ratio becomes of the number of blue stickers to red stickers is 4 : 3.
How many stickers does Adam have now?
|
Make p the same (1) x 3 = (3) |
(1) Blue |
(2) Red |
Make p the same (2) x 4 = (4) |
Before |
21 u |
7 u |
3 u |
12 u |
Change |
+ 180 |
+ 60 |
+ 90 |
+ 360 |
After |
21 u + 180 |
7 u + 60 |
3 u + 90 |
12 u + 360 |
Comparing the blue stickers and the red stickers in the end |
12 p |
4 p |
3 p |
12 p |
7 u + 60 = 4 p --- (1)
3 u + 90 = 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 + 180 = 12 p --- (3)
(2)
x 4 12 u + 360 = 12 p --- (4)
(3) = (4)
21 u + 180 = 12 u + 360
21 u - 12 u = 360 - 180
9 u = 180
1 u = 180 ÷ 9 = 20
Number of stickers that Adam has now
= 7 u + 60 + 3 u + 90
= 7 u + 3 u + 60 + 90
= 10 u + 150
= 10 x 20 + 150
= 200 + 150
= 350
Answer(s): 350