In 2013, Sondra makes taxable gifts aggregating $300,000. Her only other taxable gifts amount to $200,000 all

Question:

In 2013, Sondra makes taxable gifts aggregating $300,000. Her only other taxable gifts amount to $200,000 all of which she made in 1997.
a. What is Sondra's 2013 gift tax liability?
b. What is her 2013 gift tax liability under the assumption that she made the $200,000 of taxable gifts in 1974 instead of 1997?