Mr. Wang deposited 800 yuan in the bank two years ago, and withdrew a total of 987.2 yuan when it matured. What is the interest rate of the time deposit for these two years?
王老师两年前把800元存入银行，到期共取出987.2元，这两年定期存款利率是多少？
<gadget id="calculator">987.2 - 800</gadget>
<output>187.2</output>

<gadget id="calculator">187.2 / 800 / 2</gadget>
<output>0.117</output>

<result>0.117</result>