84又4/19*1.375+105又5/19*0.9 =(84*19+4)*11/(19*8)+(105*19+5)*9/(19*10) =(21*19+1)*11/(19*2)+(21*19+1)*9/(19*2) =(21*19+1)*(11+9)/(19*2) =(21*19+1)*10/19 =210+10/19 (210又10/19)