The school planted 235 saplings, 15 of which did not survive, and all 15 of them survived after replanting. Find the survival rate of these saplings.
学校种了235棵树苗，其中有15棵没有成活，后来补种15棵全部成活．求这些树苗的成活率．
<gadget id="calculator">235 - 15</gadget>
<output>220</output>

<gadget id="calculator">220 + 15</gadget>
<output>235</output>

<gadget id="calculator">235 + 15</gadget>
<output>250</output>

<gadget id="calculator">235 / 250</gadget>
<output>47/50 = around 0.94</output>

<result>47/50 = around 0.94</result>