How is currency depreciation related to import tariffs?
Assume that a chinese company is selling a product for 100 RMB or 16 USD.

With the 10% tariff the cost for an american importer rises to 17.6 USD. 

If the the RMB depreciates 8% and the price in RMB is unchanged the importer pays 8% less in USD or 16.192 USD. 

Depreciating the RMB by 8% offsets (almost all of) the effect of the 10% tariff.

This calculation does not account for the fact that chinese imports get more expensive. If the good is manufactured using imported oil the cost of that oil will not be offset by the depreciated RMB.