Bài 1: Tính
a) 2763 + 152 = 2915
b) ( - 7 ) + ( - 14 ) = - (7 + 14) = -21
c) ( - 35 ) + ( - 9 ) = - (35 + 9) = -44
d) ( - 5 ) + ( - 248 ) = - (5 + 248) = -253
e) ( - 23 ) + 105 = 105 - 23 = 82
f) 78 + ( - 123 ) = - (123 - 78) = -45
g) 23 + ( - 13 ) = 23 - 13 = 10
h) ( - 23 ) + 13 = - (23 - 13) = -10
i) 26 + ( - 6 ) = 26 - 6 = 20
j) ( - 75 ) + 50 = - (75 - 50) = -25
k) 80 + ( - 220 ) = - (220 - 80) = -140
l) ( - 23 ) + ( - 13 ) = - (23 + 13) = -36
m) ( - 26 ) + ( - 6 ) = - (26 + 6) = -32
n) ( - 75 ) + ( - 50 ) = - (75 + 50) = -125