If a group of saplings are distributed to male and female students, an average of 6 trees will be planted per person; if a single batch is planted for female students, an average of 10 trees will be planted per person. A single portion is planted for boys, how many trees are planted per person on average?
一批树苗，如果分给男女生栽，平均每人栽6棵；如果单份给女生栽，平均每人栽10棵．单份给男生栽，平均每人栽几棵？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/6) - (1/10)</gadget>
<output>1/15 = around 0.066667</output>

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

<result>15</result>