(10*5-(60/4))/(1-5/60)=(50-15))/(1-1/12)=35/(11/12)=35*(12/11)=420/11=38又(2/11)分 ((60/4)-(60-11*5))/(1-5/60)=(15-(60-55))/(1-1/12)=(15-5)/(11/12)=10/(11/12)=10*(12/11)=120/11=10又(10/11)分在10时38又(2/11)分和11时10又(10/11)分时,时针与分针成直角。