You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Russian_Soviet_Federative_Socialist_Republic

Context:
Roughly 70% of the area in the RSFSR consisted of broad plains, with mountainous tundra regions mainly concentrated in the east. The area is rich in mineral resources, including petroleum, natural gas, and iron ore.

Question:
What percentage of the RSFSR was made up of plains?

70%