80°25′30″-60°30′+20°24′30″
=80°25′30″+20°24′30″-60°30′
=(80°+20°-60°)+(25′+24′-30′)+(30″+30″)
=40°+19′+60″
=40°+19′+1′
=40°+20′
=40°+(20/60)°
=40°+(1/3)°
=(121/3)°
80°25′30″-60°30′+20°24′30″
=80°25′30″+20°24′30″-60°30′
=(80°+20°-60°)+(25′+24′-30′)+(30″+30″)
=40°+19′+60″
=40°+19′+1′
=40°+20′
=40°+(20/60)°
=40°+(1/3)°
=(121/3)°