Processing a batch of parts, A needs 3 hours, B needs 5 hours, A makes 18 more parts per hour than B per hour, how many parts are there in this batch?
加工一批零件，甲需要3小时，乙需要5小时，甲每小时比乙每小时多做18个，这批零件共有多少个？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/3) - (1/5)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">18 / (2/15)</gadget>
<output>135</output>

<result>135</result>