Complex sentence: By comparison, "Exeter" was armed only with six 8-inch guns and only six of "Houston" s nine 8-inch guns remained operable after her aft turret had been knocked out in an earlier air attack.
Split into simpler sentences: By comparison, "Exeter" was armed only with six guns. While "Houston" carried nine guns, only six remained operable after her aft turret had been knocked out in an earlier air attack.