The ratio of the dividend to the divisor is 15:7, if the dividend increases by 12, the quotient is 9. What is the original dividend.
被除数和除数的比是15：7，如果被除数增加12，商是9．被除数原来是多少．
<gadget id="calculator">7 * 9</gadget>
<output>63</output>

<gadget id="calculator">63 - 15</gadget>
<output>48</output>

<gadget id="calculator">12 / 48</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 15</gadget>
<output>15/4 = around 3.75</output>

<result>15/4 = around 3.75</result>