You are not allowed to pay directly from Adsense because many can use it for spamming. As we all know many event bloggers use black-hat ways to get good Adsense earnings whereas these earning are conclusion of invalid or fake clicks, etc. Therefore, Finalized Adsense earning is valued after proper inspection. To protect from these types of fraud, Google doesn't let you use money direct from your Adsense account. You can limit your payment threshold to 100$ and get paid. You can use that money on Google Adwords.
I am currently pursuing High School and planning to pursue career in Computer. Currently, I work on one of my blog - JTech Articles.