The quotient of dividing a certain number by 13 is 7 less than 20, find a certain number.
13除某数的商比20小7，求某数．
<gadget id="calculator">20 - 7</gadget>
<output>13</output>

<gadget id="calculator">13 * 13</gadget>
<output>169</output>

<result>169</result>