1949×(1/43-1/1992)+43×(1/1949-1/1992)-1992×(1/1949+1/43)+103
=1949×1/43-1949×1/1992+43×1/1949-43×1/1992-1992×1/1949-1992×1/43+103
=1949/43-1949/1992+43/1949-43/1992-1992/1949-1992/43+103
=(1949/43-1992/43)+(43/1949-1992/1949)-(1949/1992+43/1992)+103
=-1+(-1)-1+103
=100