a)
[tex]6-14=-(14-6)=\boxed{-8}\\\\17-30=-(30-17)=\boxed{-13}\\\\15+(-7)=15-7=\boxed8\\\\4+(-9)=4-9=-(9-4)=\boxed{-5}[/tex]
b)
[tex]-12+8=-(12-8)=\boxed{-4}\\\\-9+15=15-9=\boxed6\\\\-9+20=20-9=\boxed{11}\\\\-11+9=-(11-9)=\boxed{-2}[/tex]
c)
[tex]4-(-15)=4+15=\boxed{19}\\\\6-(-9)=6+9=\boxed{15}\\\\-8-(-2)=-8+2=-(8-2)=\boxed{-6}\\\\-1-(-13)=-1+13=13-1=\boxed{12}[/tex]
d)
[tex]-4-11=-(4+11)=\boxed{-15}\\\\-10-16=-(10+16)=\boxed{-26}\\\\-3+(-8)=-(3+8)=\boxed{-11}\\\\-12+(-5)=-(12+5)=\boxed{-17}[/tex]
