0.8*46+3.5*8+9.1*2
=8*4.6+3.5*8+9.1*2
=8*(4.6+3.5)+9.1*2
=8*8.1+(8.1+1)*2
=8*8.1+8.1*2+2
=(8+2)*8.1+2
=10*8.1+2
=81+2
=83