41/2 - 2 11/12 =? 6 7/15 - 2 11/12=? 10 13/30-2 11/12=?

1)4 1/2 - 2 11/12 = 4 6/12-2 11/12=1 18/12-11/12=1 7/12;
2)6 7/15 - 2 11/12=4 28/60-55/60= 3 88/60-55/60=3 33/60=3 11/20;
3)10 13/30-2 11/12=8 26/60-55/60=7 86/60-55/60=7 31/60