您好！ (1) 边际贡献=10x250x30-6x250x30=30000(元税前利润=30000-4000-900-2000x2-50x350=3600(元) (2) 固定成本=4000+900+2000x2+50x350=26400(元)保本点销量=26400- (10-6) =6600 (小时)安全边际率= (250x30-6600) - (250x30) =12% (3) 3600= [10x (1-10%) -6] x X26400每月小时: X= (3600+26400) - (9-6) =10000 (小时)安全边际额=10000x9-26400- (9-6) x9=10800(元) 安全边际量=10800/9=1200