Answer:
before tax: $1349.99
the tax: $74.924
after tax: $1424.914
Explanation:
The total purchase price before sales tax we find when we add all the prices of the purchased items:
$300 + $800 + $249.99 = $1349.99
For the sales tax we want to know how much is 5.55% from the previous $1349.99, for this we divide $1349.99 by 100 and then multiply by 5.55%

the sales tax is $74.924
And for the last question, the total purchase price, we must add this $74.924 to the price before tax $1349.99:
$1349.99 + $74.924= $1424.914
So the total purchase price is $1424.914