Teacher Yu can type 69 words per minute. For a 900-word composition, how many more words can he type in 15 minutes?
余老师每分钟可打字69个，一份900字的作文，15分钟他可以多打多少个字．
<gadget id="calculator">69 * 15</gadget>
<output>1_035</output>

<gadget id="calculator">1_035 - 900</gadget>
<output>135</output>

<result>135</result>