In the first quarter of the biscuit factory, the sales of Type A biscuits were 180 packs, 160 packs, and 230 packs respectively in January, February, and March. The sales volume of Type B biscuits was 120 packs, 160 packs, and 230 packs respectively. How many packs of biscuits are sold on average per month?
饼干厂甲种饼干第一季度一、二、三月销售饼干量分别是180包、160包、230包，乙种饼干的销售量分别是120包、160包、230包，乙种饼干比甲种饼干的月平均销售量少多少包．
<gadget id="calculator">180 + 160 + 230</gadget>
<output>570</output>

<gadget id="calculator">570 / 3</gadget>
<output>190</output>

<gadget id="calculator">120 + 160 + 230</gadget>
<output>510</output>

<gadget id="calculator">510 / 3</gadget>
<output>170</output>

<gadget id="calculator">190 - 170</gadget>
<output>20</output>

<result>20</result>