Red Star Farm will slaughter 1,800 cattle this year, which is 1/5 more than the original plan. How many cattle were originally planned to slaughter?
红星养殖场今年出栏1800头牛，比原计划多出栏(1/5)，原计划出栏多少头牛？
<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">1_800 / (6/5)</gadget>
<output>1_500</output>

<result>1_500</result>