J.Crew好价额外5折 买了个玛丽珍鞋搭配裙子

低至2.5折+额外5折， code： SUMMER  https://www.jcrew.com/sale/women?
夏天可以买个玛丽珍鞋搭配裙子,第一次尝试这种, https://www.jcrew.com/m/womens/categories/shoes/heels/MP591?
https://www.jcrew.com/m/womens/categories/clothing/t-shirts-and-tank-tops/short-sleeve/vintage-rib-henley-t-shirt-in-stripe/MP121?

阔腿牛仔裤也好看 https://www.jcrew.com/m/womens/categories/clothing/denim/wide-leg/pintuck-denim-trouser-in-rinse-wash/MP681?

2.5折咋算出来的？