The ratio of the number of red stickers to blue stickers is 2 : 1.
After Adam buys another 10 red stickers and 80 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 7 : 6.
How many stickers does Adam have now?
|
Make p the same (1) x 6 = (3) |
(1) Red |
(2) Blue |
Make p the same (2) x 7 = (4) |
Before |
12 u |
2 u |
1 u |
7 u |
Change |
+ 60 |
+ 10 |
+ 80 |
+ 560 |
After |
12 u + 60 |
2 u + 10 |
1 u + 80 |
7 u + 560 |
Comparing the red stickers and the blue stickers in the end |
42 p |
7 p |
6 p |
42 p |
2 u + 10 = 7 p --- (1)
1 u + 80 = 6 p --- (2)
Make p the same by using the LCM of 6 and 7.
LCM of 6 and 7 is 42.
(1)
x 6 12 u + 60 = 42 p --- (3)
(2)
x 7 7 u + 560 = 42 p --- (4)
(3) = (4)
12 u + 60 = 7 u + 560
12 u - 7 u = 560 - 60
5 u = 500
1 u = 500 ÷ 5 = 100
Number of stickers that Adam has now
= 2 u + 10 + 1 u + 80
= 2 u + 1 u + 10 + 80
= 3 u + 90
= 3 x 100 + 90
= 300 + 90
= 390
Answer(s): 390