3a-1{-2b+[a-(4a-3b)]}
=3a-1{-2b+[a-4a+3b]}
=3a-1{-2b+[-3a+3b]}
=3a-1{-2b-3a+3b}
=3a-1(-3a+b)
=3a+3a-b
=6a-b
=6*(-1)-3
=-6-3
=-9