$456$ Inc has a profit margin of $12\%.$ It has a capital intensity ratio of $0\mathrm{.}80$ and its debt$/$equity ratio is $2.$ The company's net income was $$100,000$ and the company paid a dividend of $$70,000.$ What is the sustainable growth rate? why is the answer $13\mathrm{.}5\%$ instead of $15\mathrm{.}61\%?$