Dongfeng Automobile Factory produced 300 cars in the first quarter and 420 cars in the second quarter. What percentage increase in the second quarter compared with the first quarter?
东风汽车厂第一季度生产汽车300辆，第二季度生产420辆，第二季度比第一季度增产百分之几？
<gadget id="calculator">420 - 300</gadget>
<output>120</output>

<gadget id="calculator">120 / 300</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>