Sunshine Supermarket sells a basketball at a price of 50 yuan. One week later, Sunshine Supermarket lowered the price by 15%, and a week later it raised it by 30%. Xiao Gang is now thinking of buying a basketball like this. How much will he have to spend? (Only the column formula does not count)
阳光超市以50元的价格出售一种篮球，一星期后，阳光超市把售价降低了15%，再过一星期又提升了30%．小刚现在正想买一个这样的篮球，他得花多少钱？(只列式不计算)
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (3/20)</gadget>
<output>17/20 = around 0.85</output>

<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">50 * (17/20) * (13/10)</gadget>
<output>221/4 = around 55.25</output>

<result>221/4 = around 55.25</result>