(1)(-3)x(+12)
=-3×12
=-36
(2)(-2/5)x(-5/2)
=2/5×5/2
=1
(3)(-8)x(-25)x(+2)
=8×25×2
=200×2
=400
(4)1/3x(-1/3)x1/8x0x(-1/8)
=0