Was Paul alone in his ministry to the Gentiles, or did the other apostles help him?
Paul carried out his Gentile ministry alone. The Twelve apostles had no part in what he accomplished, because their ministry was confined to the nation of Israel and never extended beyond the Jordan River into pagan Gentile territory. Paul therefore could preach in regions beyond without building on another man's labors.
Les explains that Paul was out in pagan Gentile territory all by himself, and the Twelve had nothing to do with what he was accomplishing. Had the Twelve already covered Corinth, Athens, Ephesus, or Asia Minor, Paul could have built on their work, but they did not. Their ministry never went outside the nation of Israel, so every place Paul went was virgin territory. He preached the gospel in regions beyond, not boasting in another man's line of things made ready to his hand.