178°16′30″-47°30′÷6+4°12′50″×3
=178°16′30″-42°330′÷6+4°12′50″×3
=178°16′30″-7°55′+12°36′150″
=177°76'30''-7°55'+12°38'30''
=170°21'30''+12°38'30''
=182°59'60''
=183°