toy factory produced 4,200 children’s toys in October, which was 1/5 more than the original plan. How many toys were originally planned to be produced?
某玩具厂十月份生产儿童玩具4200件，比原计划多生产了(1/5)，原计划生产玩具多少件？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">4_200 / (6/5)</gadget>
<output>3_500</output>

<result>3_500</result>