The ratio of the number of red stickers to green stickers is 8 : 5.
After Adam buys another 30 red stickers and 40 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 |
40 u |
8 u |
5 u |
35 u |
Change |
+ 150 |
+ 30 |
+ 40 |
+ 280 |
After |
40 u + 150 |
8 u + 30 |
5 u + 40 |
35 u + 280 |
Comparing the red stickers and the green stickers in the end |
35 p |
7 p |
5 p |
35 p |
8 u + 30 = 7 p --- (1)
5 u + 40 = 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 40 u + 150 = 35 p --- (3)
(2)
x 7 35 u + 280 = 35 p --- (4)
(3) = (4)
40 u + 150 = 35 u + 280
40 u - 35 u = 280 - 150
5 u = 130
1 u = 130 ÷ 5 = 26
Number of stickers that Adam has now
= 8 u + 30 + 5 u + 40
= 8 u + 5 u + 30 + 40
= 13 u + 70
= 13 x 26 + 70
= 338 + 70
= 408
Answer(s): 408