Suppose there are two countries in the world, US and Japan. There are Americans in Japan, and Japanese in the US. Within the US, the market value of all the final goods and services produced by Americans is $200 billion, and the market value of all the final goods and services produced by Japanese is $20 billion. Within Japan, the market value of all the final goods and services produced by Americans is $50 billion, and the market value of all the final goods and services produced by Japanese is $100 billion. what is the GDP of Japan?