A factory plans to manufacture 550 tractors, which is 50 units more than the original plan. By what percentage?
某工厂计划制造拖拉机550台，比原计划超额了50台．超额了百分之几？
<gadget id="calculator">550 - 50</gadget>
<output>500</output>

<gadget id="calculator">50 / 500</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>