Teacher Wang from the General Affairs Office bought 112 boxes of white chalk and 89 boxes of red chalk. The yellow chalk he bought was 121 boxes less than the total number of white chalk and red chalk. How many boxes of yellow chalk did you buy?
总务处的王老师买来白粉笔112盒，红粉笔89盒，买来的黄粉笔比白粉笔和红粉笔的总数少121盒．黄粉笔买了多少盒？
<gadget id="calculator">89 - 121</gadget>
<output>-32</output>

<gadget id="calculator">112 + (-32)</gadget>
<output>80</output>

<result>80</result>