5x53-{4x[5+(a-2)x7]:3}x6=1

Răspuns :

5•53-{4•[5+(a-2)•7]:3}•6=1

5•53-[4•(5+7a-14):3]•6=1

5•53-[(4•(7a-9):3]•6=1

265-[(28a-36):3]•6=1

3•265-(28a-36)•6=3

795-168a+216=3

1008=168a

a=1008:168

a=6