The store takes back a radio. If you buy 117 yuan, you can make a profit of 30%. What is the purchase price of this radio?
商店收回一台收音机，如果买117元，可盈利30%，这台收音机的进价是多少元．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 + (3/10)</gadget>
<output>13/10 = around 1.3</output>

<gadget id="calculator">117 / (13/10)</gadget>
<output>90</output>

<result>90</result>