a) 100+(430)+2145+(-530)
= 530+2145-530
= (530-530)+2145
= 0+ 2145
= 2145
b) (-12).15
= -180
c) (-4).(+3).(-125).(-25).(+8)
= [(-4).(-25)].[(-125).(+8)].(+3)
= 100.(-1000).(+3)
= (-100000).(+3)
= -300000
d) {[160:(-2)]-2.(-40)}:2020
= {-80-2.(-40)}:2020
= { -80+80}:2020
= 0:2020
= 0