3/8:2/3 = 3/8·3/2 = (3·3)/(8·2) = 9/16.

4/7:4/9 = (4·9)/(7·4) = 9/7 = 1 2/7.

11 2/5:3 4/5 = 57/5 : 19/5 = (57·5)/(5·19) = 3.

16/17:8 = 16/7 · 1/8 = 16/(7·8) = 2/7.

12:6/8 = (12·8)/6 = 2·8 = 16.