A) 14+ (-25) + (-4) + (+15) =
1) 14+ (-25)= -11
2) -4+(+15)= 11
3) -11+11=0
b)-3,9+ (+1.2) + (-6,1)+ (+2,8)=
1) -3,9+ (+1.2)= -2,7
2) (-6,1) + (+ 2,8)= - 3,3
3) -2,7 - 3,3 = -6
c) - 7/12 + ( 1/8) + (-5/12) + (+3/4)=
1) - 7/12 + ( 1/8)= -11/24
2) (-5/12)+ (+3/4)= 1/3
3) (-11/24)+ 1/3 = 1/8