Two ships, A and B, set off from two ports at the same time. It takes 10 hours for A to complete the journey, and 15 hours for B to complete the journey. After 5 hours, the distance between the two ships is 75 kilometers. How many kilometers is the distance between the two ports?
甲乙两船同时从两港相对开出，甲船行完全程要10小时，乙船行完全程要15小时，两船开出5小时后还相距75千米．两港相距多少千米？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">5 * (1/6)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">75 / (1/6)</gadget>
<output>450</output>

<result>450</result>