40°+50°=90°
24°38'+17°18'=41°56'
56°43'-21°18'=35°25'
25°×4=100°
108°+72°=180°°
44°30'+16°20'=60°50'
70°52'-20°12'=50°40'
30°20'×3=90°60'=91°
90°°-30°=60°
57°35'+42°25'=99°60'=100°
8830'-43°50'=87°90'-43°50'=44°40'
90°:3=30°
180°-50°=130°°
60°40'+50°=110°40'
90°-32°30'=122°30'