a= about 75 cents -- This is because you would figure out what 5% is equal to (.05). Then, you would do .05 x 14.90 to get the amount of sales tax you will be paying. By doing this you will get .745 which is approximately .75 which would become 75 cents
b= $15.65 -- For this one, you would do the cents (.75) plus the total (14.90) So you would do 14.90+.75 which = 15.65.
Hope this helped :)
