The ratio of the number of red stickers to blue stickers is 6 : 5.
After Adam buys another 10 red stickers and 20 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 8 : 7.
How many stickers does Adam have now?
|
Make p the same (1) x 7 = (3) |
(1) Red |
(2) Blue |
Make p the same (2) x 8 = (4) |
Before |
42 u |
6 u |
5 u |
40 u |
Change |
+ 70 |
+ 10 |
+ 20 |
+ 160 |
After |
42 u + 70 |
6 u + 10 |
5 u + 20 |
40 u + 160 |
Comparing the red stickers and the blue stickers in the end |
56 p |
8 p |
7 p |
56 p |
6 u + 10 = 8 p --- (1)
5 u + 20 = 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 42 u + 70 = 56 p --- (3)
(2)
x 8 40 u + 160 = 56 p --- (4)
(3) = (4)
42 u + 70 = 40 u + 160
42 u - 40 u = 160 - 70
2 u = 90
1 u = 90 ÷ 2 = 45
Number of stickers that Adam has now
= 6 u + 10 + 5 u + 20
= 6 u + 5 u + 10 + 20
= 11 u + 30
= 11 x 45 + 30
= 495 + 30
= 525
Answer(s): 525