((6 1/2-1 3/4): 2 1/2)/((7-6 2/5)*3 1//2+3/4-5/12)/(3 7/11+6 4/11)

 ((6 1/2-1 3/4):2 1/2)/((7-6 2/5)*3 1/3)-(1/2+3/4-5/12)/(3 7/11+6 4/11) = 13/15

1)  6 1/2-1 3/4 = 13/2 - 7/4 = 26/4 - 7/4 =19/4
2)  19/4:2 1/2= 19/4: 5/2= 19/4*2/5=19/10

3)  7-6 2/5 = 6 5/5 - 6 2/5 = 3/5
4)  3/5*3 1/3= 3/5*10/3=2

5) 19/10:2 = 19/10:2/1 = 19/10*1/2=19/20

6)  1/2+3/4-5/12 = 6/12+9/12-5/12=10/12 = 5/6

7)  3 7/11+6 4/11 = 9 11/11 = 10

8)  5/6:10 = 5/6:10/1= 5/6*1/10=1/12

9)  19/20 - 1/12 = 57/60 - 5/60 = 52/60 = 13/15