815 + [ 95 + ( -815 ) + ( -45 ) ]
= 815 + [ 95 + ( -860 ) ]
= 815 + ( -765 )
= 50 . hk tốt...........
=[815+(-8150] + [95 + (-45)]
= 0 + 50
= 50
---------------------------Hok Tốt----------------------------
815 + [ 95 + (-815 ) + ( - 45 ) ]
=815 + [ - 720 + ( -45) ]
= 815 - 765
= 50
815+[95+(-815)+(-45)]
=815+95+(-815)+(-45)
=815+(-815)+95+(-45)
=0+50
=50