batch of trees were planted in the fifth grade, among which 390 survived and 10 did not survive. What is the survival rate of this batch of trees?
五年级植树一批，其中成活的有390棵，有10棵没有成活，这批树的成活率是多少？
<gadget id="calculator">390 + 10</gadget>
<output>400</output>

<gadget id="calculator">390 / 400</gadget>
<output>39/40 = around 0.975</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(39/40) * 1</gadget>
<output>39/40 = around 0.975</output>

<result>39/40 = around 0.975</result>