(i) 45 : 30 = 24 : 16 (3 : 2 is its simplest form)
Other three proportions are:
45 : 24 = 30 : 16 (15 : 8 is its simplest form)
30 : 45 = 16 : 24 (2 : 3 is its simplest form)
16 : 30 = 24 : 45 (8 : 15 is its simplest form)
(ii) 12 : 18 = 14 : 21 (2 : 3 is its simplest form)
Other three proportions are:
12 : 14 = 18 : 21 (6 : 7 is its simplest form)
21 : 18 = 14 : 12 (7 : 6 is its simplest form)
18 : 12 = 21 : 14 (3 : 2 is its simplest form)