The first air-cushion tourist boat manufactured in my country travels 57.9 kilometers per hour, which is 28.2 kilometers per hour faster than ordinary yachts. How many kilometers per hour does ordinary yachts travel?
我国制造的第一艘海上气垫旅游艇每小时行57.9千米，比普通游艇每小时快28.2千米，普通游艇每小时行多少千米？
<gadget id="calculator">57.9 - 28.2</gadget>
<output>29.7</output>

<result>29.7</result>