The transaction volume on the first day reached 450 million yuan, and the second day decreased (1/9) compared to the first day. How many billion yuan was the total transaction volume in the first two days of the Western Specialty Products Fair?
第一天交易额达4.5亿元，第二天比第一天减少(1/9)．西部特产交易会前两天的交易额一共有多少亿元？
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 - (1/9)</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">4.5 * (8/9)</gadget>
<output>4</output>

<gadget id="calculator">4 + 4.5</gadget>
<output>8.5</output>

<result>8.5</result>