a)15√7+3{-4√3+5[2√7+3(3√3-7)]}=
=15√7+3{-4√3+5[2√7+9√3-21]}=
=15√7+3{-4√3+10√7+45√3-105}=
=15√7-12√3+30√7+135√3-315=
=45√7+123√3-315=
=3(15√7+41√3-105)
b)2√3-7{8√2-4[5√3+3(4√2-3√3)]:8}=
=2√3-7{8√2-4[5√3+12√2-9√3]:8}=
=2√3-7{[8√2-20√3-48√2+36√3]:8}=
=2√3-7{[-40√2+16√3]:8}=
=2√3-7(2√3-5√2)=
=2√3-14√3+35√2=
=35√2-12√3