6 :10 = 3 : 5
24 : 40 = 3 : 5
36 : 60 = 3 : 5
42 : 70 = 3 : 5
All the ratio in the table works out to be 3 : 5 in its lowest term
Option 1 = 18 : 20 = 9 : 10
Option 2 = 30 : 20 = 3 : 2
Option 3 = 18 : 30 = 3 : 5
Option 4 = 50 : 30 = 5 : 3
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Answer : Option C
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