A workshop needs to process 3960 parts, 3 workers processed 1320 parts in 10 hours, and the rest were completed within 15 hours. How many workers are needed?
某车间需要加工3960个零件，3个工人10小时加工了1320个，其余的要求在15小时内完成，需要增加多少个工人．
<gadget id="calculator">44 * 15</gadget>
<output>660</output>

<gadget id="calculator">2_640 / 660</gadget>
<output>4</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<result>1</result>