The ratio of the divisor to the dividend is 1:4, the sum of the dividend, the divisor and the quotient is 12.5, what is the dividend.
除数和被除数的比是1：4，被除数、除数与商的和是12.5，被除数是多少．
<gadget id="calculator">12.5 - 4</gadget>
<output>8.5</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">8.5 / 5</gadget>
<output>1.7</output>

<gadget id="calculator">1.7 * 4</gadget>
<output>6.8</output>

<result>6.8</result>