Students in grades 4, 5, and 6 of a certain school donated money to the earthquake-stricken area. The amount donated by grade 4 is (2/3) the amount donated by grades 5 and 6, and the amount donated by grade 5 is the amount donated by grades 4 and 6 (3 /5), the known donation amount for the sixth grade is 2700 yuan. How much did the three grades donate in total?
某学校四、五、六年级同学向地震灾区捐款，四年级捐款数是五、六两个年级捐款数的(2/3)，五年级捐款数是四、六两个年级捐款数的(3/5)，已知六年级捐款数为2700元．这三个年级共捐款多少元？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 - (2/5) - (3/8)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">2_700 / (9/40)</gadget>
<output>12_000</output>

<result>12_000</result>