A total of 90 white rulers and green rulers are in a container. The ratio of white rulers to green rulers was 1 : 9. Some black rulers and red rulers were put into the container. For every 3 green rulers that were already in the container, 7 red ones were added. Then, the final number of white rulers and black rulers was
15 the final number of green rulers and red rulers. Find the total number of black and red rulers.
Black rulers |
White rulers |
Green rulers |
Red rulers |
|
1x1 |
9x1 |
|
|
|
3x3 |
7x3 |
1x6 |
5x6 |
5 u |
1 u |
9 u |
21 u |
The number of green rulers is repeated. Make the number of green rulers the same. LCM of 9 and 3 is 9.
The total number of green rulers and red rulers is repeated. Make the total number of green and red rulers the same. LCM of 30 and 5 is 30.
Total number of white rulers and green rulers
= 1 u + 9 u
= 10 u
10 u = 90
1 u = 90 ÷ 10 = 9
Total number of black and red rulers
= 5 u + 21 u
= 26 u
= 26 x 9
= 234
Answer(s): 234