A factory completed 85% of the plan in the first half of the month, and completed (1/2) of the plan in the second half of the month. How much is the increase in production this month compared to the plan?
某厂上半月完成计划的85%，下半月完成计划的(1/2)，这个月比计划增产多少
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) - 1</gadget>
<output>-1/2 = around -0.5</output>

<gadget id="calculator">(17/20) + (-1/2)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>