A garment factory produces 7,800 sets of girls' and children's clothing in January, and produces 1,800 sets of boys' and children's clothing three times less than girls' and children's clothing. How many sets of boys' and children's clothing are produced?
某服装厂一月份生产女童装7800套，生产的男童装比女童装的3倍少1800套，生产男童装多少套？
<gadget id="calculator">7_800 * 3</gadget>
<output>23_400</output>

<gadget id="calculator">23_400 - 1_800</gadget>
<output>21_600</output>

<result>21_600</result>