4/7 : 5/9. ;3/8:9/6. ; 7 11/12:3. 1/6 ; 48:12/13. ; 15/16: 5

1) 4/7 : 5/9 = 4/7 * 9/5 = (4 * 9)/(7 * 5) = 36/35;

2) 3/8 : 9/6 = 3/8 * 6/9 = (3 * 6)/(8 * 9) = 1/4;

3) 7 11/12 : 3 1/6 = (7 * 12 + 11)/12 : (3 * 6 + 1)/6 = (84 + 11)/12 : (18 + 1)/6 = 95/12 : 19/6 = 95/12 * 6/19 = (95 * 6)/(12 * 19) = (5 * 6)/12 = 5/2;

4) 48 : 12/13 = 48 * 13/12 = 4 * 13 = 52;

5) 15/16 : 5 = 15/16 * 1/5 = 3/16.