a) (7/9+17/6)-(5/6-1/18)= b) (17/24+5/36)-(5/60-1/18)= c) (4 7/9-1 1/2)-(15/16-1/24)= d) (7/9+17/10-1/18)-(13/27-1/18)= e) (13/63+17/45)-(5/36-127)= f) (7/16+17/5-1/40)-(5/8-3/5)=