a) 37.24+37.76+63.79+21.63
= 37(24+76)+63(79+21)
= 37.100+63.100
= (37+63)100
= 100.100
= 10000
b) 101+(-60)+29+(-40)
= (101+29)+(-60-40)
= 130-100
= 30
c) 40+(139-172+99)-(139+199-127)
= 40+139-172+99-139-199+127
= (139-139)+(-127+127)+(99-199)+40
= 0+0-100+40
= -60
d) (158.129-158.39):180
= [158(129-39)]:180
= (150.90):180
= 75
=