The ratio of the number of red stickers to green stickers is 9 : 5.
After Adam buys another 20 red stickers and 80 green stickers,
the ratio becomes of the number of red stickers to green stickers is 7 : 5.
How many stickers does Adam have now?
|
Make p the same (1) x 5 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 7 = (4) |
Before |
45 u |
9 u |
5 u |
35 u |
Change |
+ 100 |
+ 20 |
+ 80 |
+ 560 |
After |
45 u + 100 |
9 u + 20 |
5 u + 80 |
35 u + 560 |
Comparing the red stickers and the green stickers in the end |
35 p |
7 p |
5 p |
35 p |
9 u + 20 = 7 p --- (1)
5 u + 80 = 5 p --- (2)
Make p the same by using the LCM of 5 and 7.
LCM of 5 and 7 is 35.
(1)
x 5 45 u + 100 = 35 p --- (3)
(2)
x 7 35 u + 560 = 35 p --- (4)
(3) = (4)
45 u + 100 = 35 u + 560
45 u - 35 u = 560 - 100
10 u = 460
1 u = 460 ÷ 10 = 46
Number of stickers that Adam has now
= 9 u + 20 + 5 u + 80
= 9 u + 5 u + 20 + 80
= 14 u + 100
= 14 x 46 + 100
= 644 + 100
= 744
Answer(s): 744