A total of 18 red folders and green folders are in a container. The ratio of red folders to green folders was 1 : 2. Some black folders and purple folders were put into the container. For every 4 green folders that were already in the container, 3 purple ones were added. Then, the final number of red folders and black folders was
67 the final number of green folders and purple folders. Find the total number of black and purple folders.
| Black folders |
Red folders |
Green folders |
Purple folders |
| |
1x2 |
2x2 |
|
| |
|
4x1 |
3x1 |
| 6x1 |
7x1 |
| 4 u |
2 u |
4 u |
3 u |
The number of green folders is repeated. Make the number of green folders the same. LCM of 2 and 4 is 4.
The total number of green folders and purple folders is repeated. Make the total number of green and purple folders the same. LCM of 7 and 7 is 7.
Total number of red folders and green folders
= 2 u + 4 u
= 6 u
6 u = 18
1 u = 18 ÷ 6 = 3
Total number of black and purple folders
= 4 u + 3 u
= 7 u
= 7 x 3
= 21
Answer(s): 21
