Answer:
a is correct
(purchase price) x (percent sales tax); then added to the original amount
Explanation:
When we buy some product. We have to pay tax on their purchasing amount. Tax always calculate as percentage.
First we find percentage of sales tax on purchase price which called sale tax value
Now we add sale tax amount into purchase value to get final payment of product.
Let original or purchase price of any product be p and sale tax on that product is s%
Sale tax value = s% of p = ps/100
Final price to pay = p + ps/100
Hence, (purchase price) x (percent sales tax); then added to the original amount