15-[1-(-20-4)]
=15-[1+24]
=15-25
=-10
(-40)-28-(-19)+(-24)
=-40-28+19-24
= -68+19-24
=-49-24
=-73 22.54+(-4.4)+(-12.54)+4.4
=22.54-4.4-12.54+4.4
=(22.54-12.54)+(-4.4+4.4)
=10望釆纳