The number of castors planted by the students is 75% of that of sunflowers, and 210 more sunflowers are planted than castors. How many sunflowers are there?
同学们种蓖麻的棵数是向日葵的75%，种向日葵比蓖麻多210棵．向日葵有多少棵．
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">210 / (1/4)</gadget>
<output>840</output>

<gadget id="calculator">840 + 210</gadget>
<output>1_050</output>

<result>1_050</result>