There are about 700 species of freshwater fish in my country, which is 300 species less than 50% of marine fish. How many types of marine fish are there?
我国淡水鱼大约有700种，比海洋鱼类的50%少300种．海洋鱼类大约有多少种？
<gadget id="calculator">700 + 300</gadget>
<output>1_000</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1_000 / (1/2)</gadget>
<output>2_000</output>

<result>2_000</result>