Question 387393
For every 7 marbles, 3 are orange and 4 are red

If the the bag contains 18 (6*3) orange marbles, it must contain 6*4=24 red marbles

CK
3/7 = 18/42
3/7 = 3/7

Another way:
Let x= number of red marbles, then:
3/4 = 18/x
3x=72
x=24
Hope this helps--ptaylor