Final answer:
The purpose of the letter was to express support and solidarity between the Revolutionary Action Movement and the Vietnamese Front of National Liberation in their shared struggle against oppression.
Step-by-step explanation:
The purpose of the letter written by the Revolutionary Action Movement (RAM) to the Vietnamese Front of National Liberation in 1964 was to express support and solidarity. The RAM was a civil rights organization in the United States that sought to align itself with other liberation movements around the world, including the Vietnamese struggle against colonialism and imperialism. By reaching out to the Vietnamese Front of National Liberation, the RAM aimed to establish a connection and show their shared commitment to fighting oppression.