Elisa grew up speaking Spanish, but learned to speak English as an adult, and she now works as a translator for a U.S. company that has frequent business interactions with South American businesses. Elisa's translating skills are good, and the company typically relies on her alone to do their translating. However, they are currently involved in negotiating an extremely important contract and need the wording in Spanish to be exactly right, so they hire George, a freelance translator and native English speaker to help. Elisa translates the English message into Spanish, and George translates the Spanish message back into English. They then compare the original message with George's translation to make sure they match. What process have Elisa and George completed?