On New Year's Day, the shopping mall has an activity "paying 300 yuan in cash for a single item and getting a coupon of 160 yuan" (coupons can be used together with cash when shopping). Xiaohong's mother wants to buy a coat for 510 yuan, a pair of trousers for 180 yuan, and a pair of shoes for 350 yuan. After Xiaohong's mother bought these items, she had to pay at least how many yuan in cash. Please tell me about the shopping order and payment method of Xiaohong's mother.
商场元旦搞活动"单件商品付现金满300元送赠券160元"(赠券在购物时可和现金一起用)．小红妈妈要买一件大衣510元，一条裤子180元，一双鞋子350元．小红妈妈买好这些物品后，最少要付现金多少元．请讲述一下小红妈妈购物的顺序和付费的方法．
<gadget id="calculator">350 + 350 + 20</gadget>
<output>720</output>

<result>720</result>