Question

12•{145:29+3•[15-(142:71+25•10):28)]}

Answer 1

12*{145:29+3*[15-(2+250):28]]}=
=12*[145:29+3*(15-252:28)]=
=12*[145:29+3*(14-9)]=
=12*(145:29+3*5)=
=12*(5+15)=
=12*20=
=240.