We have,
log10(3!+2!×6!−9!÷7!)−3
⇒−3log10(3!+2!×6!−9!7!)[∵logaxn=nlogax]
⇒−3log10(6+1440−9×8)
⇒−3log10(6+1440−72)
⇒−3log10(1374)
⇒−3×3.13798
⇒−9.413
Hence, this is the answer.