Xiao Ming participated in four Chinese tests, with an average score of 68. He wants to raise his five-time average score to over 70 after the next Chinese test, so how many points should he score at least in the next test?
小明参加了四次语文测验，平均成绩是68分．他想在下一次语文测验后，将五次的平均成绩提高到70分以上，那么，在下次测验中，他至少要得多少分？
<gadget id="calculator">70 * 5</gadget>
<output>350</output>

<gadget id="calculator">68 * 4</gadget>
<output>272</output>

<gadget id="calculator">350 - 272</gadget>
<output>78</output>

<result>78</result>