The ratio of the number of red stickers to green stickers is 3 : 1.
After Adam buys another 40 red stickers and 90 green stickers,
the ratio becomes of the number of red stickers to green stickers is 7 : 4.
How many stickers does Adam have now?
|
Make p the same (1) x 4 = (3) |
(1) Red |
(2) Green |
Make p the same (2) x 7 = (4) |
Before |
12 u |
3 u |
1 u |
7 u |
Change |
+ 160 |
+ 40 |
+ 90 |
+ 630 |
After |
12 u + 160 |
3 u + 40 |
1 u + 90 |
7 u + 630 |
Comparing the red stickers and the green stickers in the end |
28 p |
7 p |
4 p |
28 p |
3 u + 40 = 7 p --- (1)
1 u + 90 = 4 p --- (2)
Make p the same by using the LCM of 4 and 7.
LCM of 4 and 7 is 28.
(1)
x 4 12 u + 160 = 28 p --- (3)
(2)
x 7 7 u + 630 = 28 p --- (4)
(3) = (4)
12 u + 160 = 7 u + 630
12 u - 7 u = 630 - 160
5 u = 470
1 u = 470 ÷ 5 = 94
Number of stickers that Adam has now
= 3 u + 40 + 1 u + 90
= 3 u + 1 u + 40 + 90
= 4 u + 130
= 4 x 94 + 130
= 376 + 130
= 506
Answer(s): 506