What is the product of subtracting 30 from 50 and multiplying by 200?
50减去30的差，再去乘200，积是多少？
<gadget id="calculator">50 - 30</gadget>
<output>20</output>

<gadget id="calculator">20 * 200</gadget>
<output>4_000</output>

<result>4_000</result>