Put them in order from the lowest ratio to the highest ratio
20:10
20:30
10:10
20:10 = 2
20:30 = 2/3
10:10 = 1
Therefore, since 2/3 < 1 < 2, then 20:30 < 10:10 < 20:10
20:10
20:30
10:10
20:30 = 2/3
10:10 = 1
Therefore, since 2/3 < 1 < 2, then 20:30 < 10:10 < 20:10