-n+(3.8-n)+4.3 при n= 4/5
=-n+3.8-n+4.3=-2n+8.1= при n=4/5 = -1.6+8.1= 6.5
N =4/5=0.8 -0.8+(3.8-0.8)+4.3=-0.8+3+4.3=2.2+4.3=6.5=13/2=6 целых 1/2