There are 210 more ducks than chickens, and the ratio of the number of chickens to the number of ducks is 2:5. How many ducks and chickens are there altogether?
鸭比鸡多210只，鸡的只数和鸭的只数比是2：5．鸭和鸡共有多少只？
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">210 / 3</gadget>
<output>70</output>

<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">70 * 7</gadget>
<output>490</output>

<result>490</result>