It is known that the quotient of two numbers is 4, and the difference between these two numbers is 39, so what is the smaller number of these two numbers?
已知两个数的商是4，而这两个数的差是39，那么这两个数中较小的数是多少．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">39 / 3</gadget>
<output>13</output>

<result>13</result>