bài 5 :
a) ( 5674 - 74 ) - 5674
= 5674 - 74 - 5674
= ( 5674 - 5674 ) - 74
= 0 - 74
= -74
b) ( - 1075 ) - ( 29 - 1075 )
= -1075 - 29 + 1075
= ( -1075 + 1075 ) - 29
= 0 - 29
= -29
c) ( 18 + 29 ) + ( 158 - 18 - 29 )
= 18 + 29 + 158 - 18 - 29
= ( 18 - 18 ) + ( 29 - 29 ) + 158
= 0 + 0 + 158
= 158
d) ( 13 - 135 + 49 ) - ( 13 + 49 )
= 13 - 135 + 49 - 13 - 49
= ( 13 - 13 ) - 135 + ( 49 - 49 )
= 0 - 135 + 0
= 0 - 135
= -135