7.8×7.8-6.8-7.8=7.8×(7.8-1)-6.8=7.8×6.8-6.8=6.8×(7.8-1)=6.8×6.8=46.24
=7.8x(7.8-1)-6.8=7.8x6.8-6.8=6.8x(7.8-1)=6.8x6.8=(7-0.2)x6.8=47.6-1.36=46.24
=7.8×(7.8-1)-6.8=7.8×6.8-6.8=(7.8-1)×6.8=6.8×6.8=46.24