FOB net price =CIF- freight-premium = 20000-3160-312 =16528 USD,

Tax refund = [117000/(1+17%)] x9% = 9000 yuan,

Total RMB cost =117000+17000x10%-9000 =1/9700 yuan,

Exchange cost =119700/16528 = 7.24.

Profit-loss ratio = [(16528x7.85-119700)/19700] x100% = 8.39%.