The three workshops of the toy factory jointly make a batch of toys. The first workshop makes 2/7 of the total number, the second workshop makes 1600 toys, and the third workshop makes half of the total number of the first and second workshops. How many toys are there in total?
玩具厂三个车间共同做一批玩具，第一车间做了总数的(2/7)，第二车间做了1600个，第三车间做的个数是一、二车间总和的一半．这批玩具共有多少个？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1_600 * (1/2)</gadget>
<output>800</output>

<gadget id="calculator">1_600 + 800</gadget>
<output>2_400</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(2/7) * (1/2)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 - (2/7) - (1/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">2_400 / (4/7)</gadget>
<output>4_200</output>

<result>4_200</result>