The concert hall has 800 seats. A total of 300 middle-class seats. The fare is 40 yuan. The rest are second-class seats. Each ticket costs 30 yuan. If the concert is sold out. How much can you earn?
音乐厅有800个座位．共中甲等座位300个．票价40元．其余为乙等座位．每张票价为30元．音乐会如果把票卖完．可以收入多少元？
<gadget id="calculator">300 * 40</gadget>
<output>12_000</output>

<gadget id="calculator">800 - 300</gadget>
<output>500</output>

<gadget id="calculator">500 * 30</gadget>
<output>15_000</output>

<gadget id="calculator">12_000 + 15_000</gadget>
<output>27_000</output>

<result>27_000</result>