а) -2/7 (-1.5) (-1.2/5) 8.1
= -2/7 (-1.5) (-0.24) 8.1
= -0.428571 (-0.24) 8.1
= 0.102857 * 8.1
= 0.8318

б) -0.18 (-6.3) (-4/5) (-3/7)
= -0.18 6.3 0.8 0.428571
= -1.134 * 0.342857
= -0.38828571429