3 7/15*0.25+5/6-1 2/5;
5 .4:(3/20+0.75)

=3 7/15×25/100+5/6-1 2/5==52/15×1/4+5/6-7/5=13/15+5/6-7/5==26/30+25/30-42/30=9/30=3/10₩₩₩₩₩₩=5 4/10÷(3/20+75/100)==5 2/5÷(3/20+3/4)=27/5÷(3/20+15/20)==27/5÷18/20=27/5÷9/10=27/5×10/9=6