10.27一0.34+1.73一2.66=10.27+1.73-(0.34+2.66)=12-3=92.39x5.3+23.9x0.45+239=2.39x5.3+2.39x4.5+239=2.39x(5.3+4.5)+239=2.39x(10-0.2)+239=262.422