How do you solve this? thank you

A company wants to expand for the next few years without raising any external financing. It would like to grow the assets on its balance sheet by 9% each year (therefore it looking to maintain an "internal growth rate" of .09). The company's management believes that it can maintain a profit margin of .28 and a total asset turnover of .38. Given these projections, what percentage of net income would have to be reinvested each year (i.e., what retention ratio would be needed) in order for the company to meet its goal of 9% expansion each year