1)8×(-3)+(-7) = -24 + (-7) = -31
2)(-2)×(-5)-12 = 10 - 12 = -2
3) 35-(-7)×6 = 42 × 6 = 252
4)32:(-4)+5 = -8 + 5 = -3
5)64:(-16)-9 = -4 - 9 = -13
6)17-(-12):4 = 29 : 4 = 7,25
7) (-21):(-3)-9 = 7 - 9 = -2
8) (-42):6+10 = -7 + 10 = 3
9) 27-(-15):3 = 42 : 3 = 14