The ratio of the number of red stickers to blue stickers is 2 : 1.
After Adam buys another 50 red stickers and 70 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 7 : 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 7 = (4) |
Before |
10 u |
2 u |
1 u |
7 u |
Change |
+ 250 |
+ 50 |
+ 70 |
+ 490 |
After |
10 u + 250 |
2 u + 50 |
1 u + 70 |
7 u + 490 |
Comparing the red stickers and the blue stickers in the end |
35 p |
7 p |
5 p |
35 p |
2 u + 50 = 7 p --- (1)
1 u + 70 = 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 10 u + 250 = 35 p --- (3)
(2)
x 7 7 u + 490 = 35 p --- (4)
(3) = (4)
10 u + 250 = 7 u + 490
10 u - 7 u = 490 - 250
3 u = 240
1 u = 240 ÷ 3 = 80
Number of stickers that Adam has now
= 2 u + 50 + 1 u + 70
= 2 u + 1 u + 50 + 70
= 3 u + 120
= 3 x 80 + 120
= 240 + 120
= 360
Answer(s): 360