The fifth grade students participated in the writing competition and recitation competition activities of the school art month. The number of participants accounted for 90% of the total number of participants in the whole grade. Among them, the number of participants in the writing competition accounted for 40% of the total number of participants, and the number of participants in the reading competition accounted for ( 3/4), there are 108 people participating in both competitions, how many people in the fifth grade?
五年级同学参加校艺术月的写字比赛和朗诵比赛活动，参赛人数占全年级总数的90%，其中参加写字比赛的人数占参赛总人数的40%，参加朗读比赛的人数占参赛总人数的(3/4)，两种比赛都参加的有108人，五年级共有多少人？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/4) - 1</gadget>
<output>-1/4 = around -0.25</output>

<gadget id="calculator">(2/5) + (-1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">108 / (3/20)</gadget>
<output>720</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">720 / (9/10)</gadget>
<output>800</output>

<result>800</result>