解【1】
55°28′+42°32′-13°27′
=(55°+42°-13°)+(28′+32′-27′)
=84°+33′
=84°33′
解【2】
15°51′×2÷5
=(15°+51′)×2/5
=15°×2/5+51′×2/5
=6°+20.4′
=6°+20′+0.4′
=6°+20′+(0.4×60)″
=6°+20′+24″
=6°20′24″
解【1】
55°28′+42°32′-13°27′
=(55°+42°-13°)+(28′+32′-27′)
=84°+33′
=84°33′
解【2】
15°51′×2÷5
=(15°+51′)×2/5
=15°×2/5+51′×2/5
=6°+20.4′
=6°+20′+0.4′
=6°+20′+(0.4×60)″
=6°+20′+24″
=6°20′24″