[ t ]SI=s
a)4h30min+2h55min=6h85min=7h25min=
=7×3600s+25×60s=25200s+1500s=26700s
b)1h4min20s+6h59min33s=7h63min53s=
8h3min53s=8×3600s+3×60s+53s=
=28800s+180s+53s=29033s
c)22h25min-18h38min=3h47min=
=3×3600s+47×60s=10800s+2820s=
=13620s
[A]SI=m2
d)0,003km2+46078dm2=3000m2+460,78m2=
=3460.78m2