a) 33. (17-5) - 17 . ( 33-5).
= 33.17 - 33.5 - 17.33 + 17.5
= 33.17 - 17.33 - 33.5 + 17.5
= 33.(17 - 17) + 5.( -33+17)
= 33.0 + 5.(-16)
= 0 + (-80)
= -80
b)324+324+ [112-(112+324)]
= 324 + 324 + 112 - 112 + 324
= 324 + 324 + 324 + 112 - 112
= (324 + 324 + 324) + (112 - 112)
= 972 + 0
= 972