The ratio of the number of green stickers to red stickers is 7 : 4.
After Adam buys another 30 green stickers and 90 red stickers,
the ratio becomes of the number of green stickers to red stickers is 8 : 7.
How many stickers does Adam have now?
|
Make p the same (1) x 7 = (3) |
(1) Green |
(2) Red |
Make p the same (2) x 8 = (4) |
Before |
49 u |
7 u |
4 u |
32 u |
Change |
+ 210 |
+ 30 |
+ 90 |
+ 720 |
After |
49 u + 210 |
7 u + 30 |
4 u + 90 |
32 u + 720 |
Comparing the green stickers and the red stickers in the end |
56 p |
8 p |
7 p |
56 p |
7 u + 30 = 8 p --- (1)
4 u + 90 = 7 p --- (2)
Make p the same by using the LCM of 7 and 8.
LCM of 7 and 8 is 56.
(1)
x 7 49 u + 210 = 56 p --- (3)
(2)
x 8 32 u + 720 = 56 p --- (4)
(3) = (4)
49 u + 210 = 32 u + 720
49 u - 32 u = 720 - 210
17 u = 510
1 u = 510 ÷ 17 = 30
Number of stickers that Adam has now
= 7 u + 30 + 4 u + 90
= 7 u + 4 u + 30 + 90
= 11 u + 120
= 11 x 30 + 120
= 330 + 120
= 450
Answer(s): 450