Xiao Ming rides a motorcycle from A to B. The ratio of the distance traveled to the whole journey is 1:3. If he travels another 15 kilometers, he can travel half of the whole journey. How far is it from A to B?
小明骑摩托车从甲地到乙地，已行的路程与全程的比是1：3，如果再行15千米，就可以行全程的一半．甲地到乙地有多远？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">15 / (1/6)</gadget>
<output>90</output>

<result>90</result>