a) 18.17 - 3.6.7

= 18.17 - 18.7

18.(17 - 7) = 18.10 = 180

b)54 - 6.(17 + 9)

= 9.6 - 6.26 = 6.(9 - 26)

= 6.(-17) = -102

c)33.(17 - 5) - 17.(33 - 5)

= 33.17 - 33.5 - 17.33 + 17.5

= (33.17 - 17.33) + (-33.5 + 17.5)

= 0 + 5.(-33 + 17)

= 5.(-16) = -80

=