Xiao Ding Ding does oral calculations. If he does 24 questions a day, he can finish it in 15 days. In fact, Ding Ding does 6 more questions a day. How many days in advance?
小丁丁做口算题，如果每天做24题，15天可以做完，实际小丁丁每天多做6题．提前几天做完？
<gadget id="calculator">24 * 15</gadget>
<output>360</output>

<gadget id="calculator">6 * 15</gadget>
<output>90</output>

<gadget id="calculator">90 - 360</gadget>
<output>-270</output>

<gadget id="calculator">360 + (-270)</gadget>
<output>90</output>

<gadget id="calculator">24 + 6</gadget>
<output>30</output>

<gadget id="calculator">90 / 30</gadget>
<output>3</output>

<result>3</result>