（-47.65）x2又6/11+(-37.15)x(-2又6/11)+10.5x(-1又5/11).
=（-47.65）x2又6/11+(+37.15)x(+2又6/11)+10.5x(-1又5/11).
=2又6/11X(-47.65+37.15)+10.5x(-1又5/11).
=2又6/11X(-10.5)+10.5x(-1又5/11).
=2又6/11X(-10.5)+(-10.5)x(+1又5/11)
=(-10.5)(2又6/11+1又5/11)
==(-10.5)x4
=-42