Verified Answer :

Amount of purchase that Steve made = $40
Percentage of tax that Steve needs to pay = 10%
Then
Amount of tax that Steve needs to pay for the purchase = (10/100) 40
                                                                                          = 1
4 dollars
                                                                                          = 4 dollars
Then
The total amount including tax
that Steve needs to pay for the purchase = (40 + 4) dollars
                                                                   = 44 dollars

So the dollar amount of tax that Steve had to pay is $4 and
the total amount that Steve had to pay was $44.