A kind of watch first increases in price (1/10), and then decreases in price (1/10). At this time, the selling price is 49.5 yuan. What is the original price of this watch?
一种手表，先涨价(1/10)，后来又降价(1/10)，此时售价是49.5元，这种手表的原价是多少元？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<gadget id="calculator">49.5 / (9/10) / (11/10)</gadget>
<output>50</output>

<result>50</result>