Hazel has a bag containing some red and green stamps. If she adds in 6 red stamps, 30% of the stamps in the bag are green. If she adds in another 35 green stamps, 40% of the stamps in the bag are green. How many red stamps are in the bag?
| |
Red stamps |
Green stamps |
| Before |
21 u - 6 |
9 u |
| Change 1 |
+ 6 |
|
| After 1 |
7x3 =
21 u |
3x3 =
9 u |
| Change 2 |
|
+ 35 |
| After 2 |
3x7 =
21 u |
2x7 =
14 u |
30% =
30100 =
31040% =
40100 =
25The number of red stamps remains unchanged at the second change when she adds in another 35 green stamps. Make the number of red stamps the same at the second change. LCM of 7 and 3 is 21.
Number of green stamps added
= 14 u - 9 u
= 5 u
5 u = 35
1 u = 35 ÷ 5 = 7
Number of red stamps at first
= 21 u - 6
= 21 x 7 - 6
= 147 - 6
= 141
Answer(s): 141
