The engineering team wants to build a 7.4-kilometer-long highway. It has been built for 12 days, with an average of 0.35 kilometers per day. The rest will be completed within 8 days. How many kilometers will be built on average per day?
工程队要筑一条长7.4千米的公路，已经筑了12天，平均每天筑0.35千米，剩下的要在8天内完成，平均每天至少要筑多少千米？
<gadget id="calculator">0.35 * 12</gadget>
<output>4.2</output>

<gadget id="calculator">7.4 - 4.2</gadget>
<output>3.2</output>

<gadget id="calculator">3.2 / 8</gadget>
<output>0.4</output>

<result>0.4</result>