1) 185/6-(71/6+35/6)=
=113/6-(43/6+23/6)=
=113/6-66/6=
=47/6
2)(72/11-54/11)-(1/11+3/11)=
=(79/11-59/11)-4/11=
=20/11-4/11=
=16/11
3)83/15-2-(74/15-52/15)=
=123/15-30/15-(109/15-77/15)
=123/15-30/15-32/15=
=61/15
4) 98/13-4-(15/13+26/13)=
=125/13-52/13-(18/13+32/13)=
=125/13-52/13-50/13=
=23/13