Xiaoming and his younger sister move the same amount of bricks. Xiaoming moves his own bricks every minute (1/10), and his sister moves his own bricks every minute (1/15). Now they both move their own bricks at the same time. Xiao Ming went to help his sister move immediately after moving. How long did it take for both of them to complete the task?
小明和妹妹两人搬同样多的砖块，小明每分钟搬自已砖块的(1/10)，妹妹每分钟搬自已砖块的(1/15)，现在两人同时搬自已的砖块，小明搬完后立即去帮妹妹搬．多长时间，两人都完成了任务？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

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

<gadget id="calculator">1 / (1/10)</gadget>
<output>10</output>

<gadget id="calculator">(1/15) * 10</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

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

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

<gadget id="calculator">2 + 10</gadget>
<output>12</output>

<result>12</result>