The school's new teaching building originally planned to invest 800,000 yuan, but actually used 728,000 yuan. How much was saved?
学校新建教学楼，原计划投资80万元，实际用了72.8万元，这样节约了多少
<gadget id="calculator">80 - 72.8</gadget>
<output>7.2</output>

<gadget id="calculator">7.2 / 80</gadget>
<output>0.09</output>

<result>0.09</result>