a) 5+(-7)-(-4)-(-6) = 5-7+4+6 = -2+10=8
b) -4+(-2)+3-(-5+7-9+1) = -4-2+3-(2-9+1) = -6+3-(-7+1) = -9-(-6)=-9+6=3
c) 7-(-13+25+4)-(8+13-25)-(-5-3) = 7-(12+4)-(21-25)-(-8) = 7-16-(-4)+8 = -9+4+8 = 3
e) -12-(-14+18-9)-(8-15-5)-(+6+5) = -12-(4-9)-(-7-5)+11 = -12+5+12+11 = -7+23 = 17
d) 13-(5-17)-(3-10-9+12)-(3-18) = 12-(-12)-(-7-9+12)-(-15) = 24-(-16+12)+15 =
= 24-(-4)+15 = 28+15 = 43
f) (7+15-28)+(-15+21)-(13-19) = (22-28)+6-(-6) = -6+6+6 = 6
g) (-8-15+20)-(3+9-7)-(-15+23) = (-23+20)-(12-7)-8 = -3-5-8 = -8-8 = -16