The ratio of the number of red stickers to blue stickers is 9 : 7.
After Adam buys another 80 red stickers and 90 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 |
54 u |
9 u |
7 u |
49 u |
Change |
+ 480 |
+ 80 |
+ 90 |
+ 630 |
After |
54 u + 480 |
9 u + 80 |
7 u + 90 |
49 u + 630 |
Comparing the red stickers and the blue stickers in the end |
42 p |
7 p |
6 p |
42 p |
9 u + 80 = 7 p --- (1)
7 u + 90 = 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 54 u + 480 = 42 p --- (3)
(2)
x 7 49 u + 630 = 42 p --- (4)
(3) = (4)
54 u + 480 = 49 u + 630
54 u - 49 u = 630 - 480
5 u = 150
1 u = 150 ÷ 5 = 30
Number of stickers that Adam has now
= 9 u + 80 + 7 u + 90
= 9 u + 7 u + 80 + 90
= 16 u + 170
= 16 x 30 + 170
= 480 + 170
= 650
Answer(s): 650