(-12b3)(8b2) 2) (7a5b3c)(-3ab4c) 3 ) (-32a3xy3)34ax2y) 4) (-18n)(-16m2)(-5nm) 5) (-13a2bc)(-5ab2c)(-0.4abc3)

1) (-1/2b×2)(8b×2) = -b×16b= -16b²

2) (7a×5b×3c)(-3ab×4c) = 75abc × (- 12abc) = -900a²b²c²

3) ( -3/2a × 3xy×3) × 3/4ax×2y = - 27/2axy × 3/2axy = -81/4 axy = 20,25axy

4) ( -18n)( -1/6m×2)( -5mn) = -18n × ( - 1/3m)( -5nm) = 6mn × ( -5mn) = -30m²n²

5) ( -5ab × 2c)( -0,4abc×3) = -10abc × ( - 1.2abc) = 12a²b²c²