A, B, and C jointly produce a batch of parts. The parts produced by A are 1/2 of the sum of parts produced by B and C. The ratio of the sum of parts produced by A and C to the number of parts produced by B is 7:2. C produces 200 parts. How many parts did A produce?
甲乙丙三人共同生产一批零件，甲生产的零件是乙丙总和的(1/2)，甲丙生产的零件总和与乙生产零件个数的比是7：2，丙生产200个零件，甲生产了多少个零件？
<gadget id="calculator">2 + 7</gadget>
<output>9</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<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">(7/9) - (1/3)</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">200 / (4/9)</gadget>
<output>450</output>

<gadget id="calculator">450 * (1/3)</gadget>
<output>150</output>

<result>150</result>