20 students from Experimental Primary School participated in the English competition, and 7 of them scored 90 points. The total score of these 7 students accounted for (2/5) of the total score of all participating students. What is the average score of this English competition?
实验小学20个同学参加英语竞赛，得90分的有7人，这7个同学的总分占所有参赛学生总分的(2/5)，这次英语竞赛的平均分是多少？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">7 / (2/5) / 20</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">90 * (7/8)</gadget>
<output>315/4 = around 78.75</output>

<result>315/4 = around 78.75</result>