Shanghai needs a highway, 70 kilometers of which have been built, and the rest is 20 kilometers less than four times the completed one. How many kilometers is the total length of this highway?
上海要一条公路，已建成70千米，剩下的比建成的4倍少20千米，这条公路全长多少千米？
<gadget id="calculator">70 * 4</gadget>
<output>280</output>

<gadget id="calculator">280 - 20</gadget>
<output>260</output>

<gadget id="calculator">70 + 260</gadget>
<output>330</output>

<result>330</result>