To build a road, the plan is to build 90 meters per day, but the actual repair is 20 meters more than the plan every day, and the result is completed 4 days ahead of schedule. How many days did it actually take?
修一条公路，计划每天修90米，实际每天比计划多修20米，结果提前4天修完，实际修了多少天？
<gadget id="calculator">90 + 20</gadget>
<output>110</output>

<gadget id="calculator">4 / 20</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">110 * (1/5)</gadget>
<output>22</output>

<gadget id="calculator">22 - 4</gadget>
<output>18</output>

<result>18</result>