15 2/5*1 5/7+6 10/27*3 3/8=77/5*12/7 + 172/27*27/8=26,4+21,5=47,9

15 4/7-4 3/8*(1 3/7-34/35)=15 4/7-35/8*16/35=15 4/7-2=13 4/7