Divide 387 by a number, the quotient is 19, the remainder is 7, find this number.
387除以一个数，商是19，余数是7，求这个数．
<gadget id="calculator">387 - 7</gadget>
<output>380</output>

<gadget id="calculator">380 / 19</gadget>
<output>20</output>

<result>20</result>