We have,
log10(3!+2!×6!−9!÷7!)−3
⇒log10(3!+2!×6!−9!7!)−3
⇒log10(6+2×6×5×4×3×2×1−9×8×7!7!)−3
⇒log10(6+1440−72)−3
⇒−3log10(1374)
⇒−3×3.13798
⇒−9.414
Hence, this is the answer.