The ratio of the number of red stickers to blue stickers is 3 : 1.
After Adam buys another 30 red stickers and 40 blue stickers,
the ratio becomes of the number of red stickers to blue stickers is 7 : 4.
How many stickers does Adam have now?
|
Make p the same (1) x 4 = (3) |
(1) Red |
(2) Blue |
Make p the same (2) x 7 = (4) |
Before |
12 u |
3 u |
1 u |
7 u |
Change |
+ 120 |
+ 30 |
+ 40 |
+ 280 |
After |
12 u + 120 |
3 u + 30 |
1 u + 40 |
7 u + 280 |
Comparing the red stickers and the blue stickers in the end |
28 p |
7 p |
4 p |
28 p |
3 u + 30 = 7 p --- (1)
1 u + 40 = 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 + 120 = 28 p --- (3)
(2)
x 7 7 u + 280 = 28 p --- (4)
(3) = (4)
12 u + 120 = 7 u + 280
12 u - 7 u = 280 - 120
5 u = 160
1 u = 160 ÷ 5 = 32
Number of stickers that Adam has now
= 3 u + 30 + 1 u + 40
= 3 u + 1 u + 30 + 40
= 4 u + 70
= 4 x 32 + 70
= 128 + 70
= 198
Answer(s): 198