Xiao Jing wrote 87 big characters in three days, 24 on the first day, 6 fewer on the second day than on the first day, how many big characters did she write on the third?
小靖三天写了87个大字，第一天写了24个，第二天比第一天少写6个，第三写了多少个大字？
<gadget id="calculator">24 - 6</gadget>
<output>18</output>

<gadget id="calculator">87 - 24 - 18</gadget>
<output>45</output>

<result>45</result>