- (5π+2)β( - 12π+18)β( - 16π+11)
- (5π+2) - ( - 12π+18) - ( - 16π+11)
= -5π-2 +12π-18 +16π - 11
= -5π +12π +16π -2 -18 - 11
= 23i -31
= 23i - 31
