This can be a really easy problem if you know what you're doing.
We'll just start by taking the 30% off $149. That comes to $104.30.
From here, we have all the data we need to answer letters A and B.
a) If sales tax is before after the 30% off, that means that we need to calculate 5.75% and multiply it by $149. $8.57 is the answer. But we aren't done just yet. We need to add $149 and $8.57 together. That becomes $157.57. Now we take off that 30% for a grand total of $110.30.
b) If sales tax comes after the 30% off, then we'll take our result from earlier, $104.30, because it is 30% off the original price. Then we do the %5.75 of our new total, $104.30, and our tax is an extra $6. Adding this to our total will give us $110.30, the exact same total as before.
Note that I did do a bit of rounding and that the answers are so extremely close that it doesn't really make any difference. The answers for both a and b are $110.30. Those are some expensive skates.