Answer: Total purchase price of this watch is $9300.
Step-by-step explanation:
Since we have given that
Retail price of watch = $8000
Rate of sales tax = 6%
Amount of sales tax becomes

Rate of excise tax = 10%
Amount of excise tax is given by

So, Amount of watch after sales tax becomes

Amount of additional shipping charge = $20
Amount of watch after additional shipping charge becomes

Hence, Total purchase price of this watch is $9300.