The school built a teaching building. After improving the plan, the actual investment was 1.8 million yuan, which was 200,000 yuan less than the original plan. How much was the savings? How much (list or equation only, no calculation)
学校修建一座教学大楼，改进方案后，实际投资180万元，比原计划节省20万元，节省了百分之几？多少(只列式或方程，不计算)
<gadget id="calculator">180 + 20</gadget>
<output>200</output>

<gadget id="calculator">20 / 200</gadget>
<output>1/10 = around 0.1</output>

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