40°20'30''+50°10'20''=90°30'50''
55°24'36"+15°18'19"=70°42'55"
40°+50°20'51"=90°20'51"
100°40'32"+50°20'40"+20°=171°1'12"
16°14'15"-10°12'11"=6°2'4"
45°35'25"-24°30'30"=21°4'55"
180°-40°30'20"=179°59'60"-40°30'20"=139°29'40"
90°-20°35'25"=89°59'60"-20°35'15"=69°24'45"