The new year is approaching, and the promotional activities in the supermarket are very attractive. The original 180 yuan milk powder, now buy 7 bags and get 2 bags free. How much is it cheaper to buy 7 bags at a time?
新年将近，超市的促销活动很吸引人，原来180元的奶粉，现在买7袋赠2袋．一次买7袋，每袋便宜多少元？
<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">180 * (7/9)</gadget>
<output>140</output>

<gadget id="calculator">180 - 140</gadget>
<output>40</output>

<result>40</result>