A, B, C, and D work together to make a batch of parts. The number of parts made by A is half of the total work of the other three people, and the number of parts made by B is (1/3) of the total work of the other three people. The number of parts is 1/4 of the total work of the other three people. Ding made 390 parts. How many parts did the four people make in total?
甲、乙、丙、丁合做一批零件，甲做的个数是其他三个人工作总量的一半，乙做的个数是其他三个人工作总量的(1/3)，丙做的个数是其他三个人工作总量的(1/4)，丁做了390个，求四个人共做了多少个零件？
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/3) - (1/4) - (1/5)</gadget>
<output>13/60 = around 0.216667</output>

<gadget id="calculator">390 / (13/60)</gadget>
<output>1_800</output>

<result>1_800</result>