Cześć ;-)
a)
[tex]70-(60-(50-40))=\\\\=70-(60-10)=70-50=\boxed{20}[/tex]
b)
[tex]80-(70-(50-(30-10)))=\\\\=80-(70-(50-20))=\\\\=80-(70-30)=80-40=\boxed{40}[/tex]
c)
[tex]128:(32:(16:2))=\\\\=128:(32:8)=128:4=\boxed{32}[/tex]
d)
[tex]256:(64:(32:(16:4)))=\\\\=256:(64:(32:4))=\\\\=256:(64:8)=256:8=\boxed{32}[/tex]
e)
[tex](15\cdot5+25):(10+15\cdot6)=\\\\=(75+25):(10+90)=\\\\=100:100=\boxed1[/tex]
f)
[tex][15\cdot(5+25)]:[(10+15)\cdot6]=\\\\=(15\cdot30):(25\cdot6)=450:150=\boxed3[/tex]
Pozdrawiam!