The ratio of the number of red stickers to blue stickers is 3 : 1.
After Adam buys another 30 red stickers and 80 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 8 : 5.
How many stickers does Adam have now?
|
Make p the same (1) x 5 = (3) |
(1) Red |
(2) Blue |
Make p the same (2) x 8 = (4) |
Before |
15 u |
3 u |
1 u |
8 u |
Change |
+ 150 |
+ 30 |
+ 80 |
+ 640 |
After |
15 u + 150 |
3 u + 30 |
1 u + 80 |
8 u + 640 |
Comparing the red stickers and the blue stickers in the end |
40 p |
8 p |
5 p |
40 p |
3 u + 30 = 8 p --- (1)
1 u + 80 = 5 p --- (2)
Make p the same by using the LCM of 5 and 8.
LCM of 5 and 8 is 40.
(1)
x 5 15 u + 150 = 40 p --- (3)
(2)
x 8 8 u + 640 = 40 p --- (4)
(3) = (4)
15 u + 150 = 8 u + 640
15 u - 8 u = 640 - 150
7 u = 490
1 u = 490 ÷ 7 = 70
Number of stickers that Adam has now
= 3 u + 30 + 1 u + 80
= 3 u + 1 u + 30 + 80
= 4 u + 110
= 4 x 70 + 110
= 280 + 110
= 390
Answer(s): 390