(1) 53°9′+25°4+′38′′
(2) 90°-37°42′38′′
(3) 25°53′28′′×5
(4) 15°20′÷6
(1) 53°9′+25°4′38′′
=78°13′38′′
(2) 90°-37°42′38′′
=89°59′60′′-37°42′38′′
=52°17′22′′
(3) 25°53′28′′×5
=125°265′140′′
=125°267′20′′
=129°27′20′′
(4) 15°20′÷6
=920'/6
=153又3分之1′
=153′20"
=2°33′20"
90°角减去60°角等于多少度?