0.8+0.2/(1/15- 1целая 1/12+9/20)

8/10+ 2/ (10*(1/15-13/12+9/20))= 8/10+ 2/ (10*((4+65+27)/60)= 8/10+2/(10*(96/60)= 8/10+2/(10*1,6)= 8/10+2/16= 8/10+1/8=(32+5)/40=37/40