A batch of cement was shipped from the construction site. The first time I used all the cement (1/3) more than 20 bags, the second time I used the remaining (3/5) 10 bags less, and the remaining 210 bags were useless. How many packages of batch cement?
建筑工地运来一批水泥，第一次用了全部水泥的(1/3)多20包，第二次用了余下的(3/5)少10包，还剩下210包没用，这批水泥原有多少包？
<gadget id="calculator">210 - 22</gadget>
<output>188</output>

<gadget id="calculator">20 + 188</gadget>
<output>208</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/3) - (2/5)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">208 / (4/15)</gadget>
<output>780</output>

<result>780</result>