a)
6x4x14+(275-142)x3+156x(143--36)=
=24x14+133x3+156x107=
=336+399+16 699=
=735+16 699=
=17 434
b)
3x(18+12x3)+(47-32)x12+172-138=
=3x(18+36)+15x12+172-138=
=3x54+180+172-138=
=162+180+172-138=
=514-138=
=376
c)
248x(6+15)-(172-29)x13+63x(5+2x8)=
=248x21-143x13+63x21=
=5 208-1859+1 323=
=3 349+1 323=
=4 672