Answer:
 a) $190
 b) $205.96
Explanation:
a)
The tax is figured as ...
 tax = tax rate · purchase price
Then ...
 purchase price = tax/(tax rate) = $15.96/0.084
 purchase price = $190
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b)
The total price is the purchase price with tax added.
 total price = purchase price + tax
 = $190 +15.96
 total price = $205.96