6又5分之4×16.8+19.3×3又5分之1
=6.8×16.8+19.3×3.2
=6.8×16.8+16.8×6.2+2.5×3.2
=（6.8+3.2）×16.8+2.5×4×0.8
=10×16.8+10×0.8
=168+8
=176