A chemical fertilizer factory originally planned to complete a task in 14 days. Due to the extra production of 3.5 tons of fertilizer every day, the task was completed in 9 days. How many tons of fertilizer was originally planned to be produced per day.
一个化肥厂原计划14天完成一项任务，由于每天多生产化肥3.5吨，结果9天就完成任务．原计划每天生产化肥多少吨．
<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">1 / 14</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">(1/9) - (1/14)</gadget>
<output>5/126 = around 0.039683</output>

<gadget id="calculator">3.5 / (5/126) / 14</gadget>
<output>6.3</output>

<result>6.3</result>