Strings with 4 factors to get to 840

2 x 420

3 x 280

4 x 210

5 x 168

6 x 140

7 x 120

8 x 105

10 x 84

12 x 70

14 x 60

15 x 56

20 x 24

21 x 40

24 x 35

28 x 30

2 x 2 x 210

2 x 3 x 140

2 x 5 x 84

2 x 7 x 60

3 x 5 x 56

3 x 7 x 40

5 x 7 x 24

2 x 2 x 2 x 105

2 x 2 x 3 x 70

2 x 2 x 5 x 42

2 x 2 x 7 x 30

2 x 3 x 5 x 28

2 x 3 x 7 x 20

3 x 5 x 7 x 8

2 x 2 x 2 x 3 x 35

2 x 2 x 2 x 5 x 21

2 x 2 x 2 x 7 x 15

The answer is a 5/20 because if u add all of the marbles there are 20 and there are 5 red marbles so 5/20 is the answer mark as brainliest