6又4/5*31.4+43又9/10*3.2
=6.8x31.4+43.9x3.2
=6.8x31.4+(31.4+12.5)x3.2
=6.8x31.4+31.4x3.2+12.5x3.2
=31.4x(6.8+3.2)+1.25x32
=314+1.25x4x8
=354行吗?