[tex]\bold{a)} \ 0,004 \ km+27 \ dm=40 \ dm+27 \ dm=67 \ dm=\boxed{6,7 \ m}. \\ \bold{b}) \ 4 \ mm^2+0,002 \ cm^2=0,000004 \ m^2+0,0000002 \ m^2=\boxed{0,0000042 \ m^2}. [/tex]
[tex]\bold{c)} \ 10 \ dm^3+49673 \ mm^3=0,01 \ m^3+0,000049673 \ m^3=\boxed{0,010049673 \ m^3}.[/tex]
[tex]\bold{d)} \ 30 \ N+3 \ kN+3 \ mN=30 \ N+3000 \ N+0,003 \ N=\boxed{3030,003 \ N}.[/tex]
[tex]\bold{e)} \ 42 \ km/h+8 \ m/s=11,(6) \ m/s+8 \ m/s=\boxed{19,(6) \ m/s}.[/tex]