1) 79/80-(3/16+39/80)= 79/80-(15/80+39/80)=

79/80-54/80=25/80=5/16

2)7/15-(2/15+1/5)=7/15-(2/15+3/15)=7/15-5/15=2/15

3)2/45+(41/45-7/9)=2/45+(41/45-35/45)=

2/45+6/45=8/45

4)3/16+(15/16-5/8)=3/16+(15/16-10/16)=3/16+5/16=8/16=1/2

Пошаговое объяснение:

1)79/80-(3/16+39/80)=79/80-(15/80+39/80)=79/80-54/80=25/80

2)2/45+(41/45-7/9)=2/45+(41/45-35/35)=2/45+6/45=8/45

3)7/15-(2/15+1/5)=7/15-(2/15+3/15)=7/15-5/15=2/15

4)3/16+(15/16-5/8)=3/16+(15/16-10/16)=3/16+5/16=8/16=1/2