Please help with the following economic trade question

_) Consider the following: In 2020, China's GDP is $14.5 trillion, India's is $3.2 trillion and US GDP is $21 trillion. The distance between China and the US is 400, between the US and India 500, and between China and India 100. The Gravity Mode! would predict that China and the US are the largest trading partners. Assume China's annual GDP growth rate is 6 per cent, the US' is 2 per cent, and India's is 7 per cent. Use the Gravity Model to decide the pair of largest trading partners in 2040