Xiao Ming rides a bicycle from A to B for an outing, and originally planned to arrive in 8 hours. When traveling to the 90 kilometers of the whole journey, the bicycle broke down, and the speed was slower than the plan (1/5). As a result, the arrival was delayed 30 minutes from the original plan. How many kilometers per hour was originally planned?
小明骑自行车从甲地到乙地郊游，原计划8小时到达．当行至全程的90千米处时，自行车出现了故障，速度比计划慢了(1/5)，结果比原计划推迟30分钟到达，原计划每小时行多少千米？
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">0.5 / (1/4)</gadget>
<output>2</output>

<gadget id="calculator">8 - 2</gadget>
<output>6</output>

<gadget id="calculator">90 / 6</gadget>
<output>15</output>

<result>15</result>