(12 1/3-7 3/4)×6/11 (2 3/5-5/8)÷19 3/4

1)(3/4+1/5)*5/19=1/4
3/4+1/5=19/20
19/20*5/19=1/4

2) (12 1/3-7 3/4)*6/11=2 1/2
12 1/3-7 3/4=4 7/12
4 7/12*6/11=2 1/2

3) (2 3/5-5/8):19 3/4=1/10
2 3/5-5/8=1 39/40
1 39/40:19 3/4= 1/10