Riya wants to have enough saved to live off of 80% of her current annual gross wage, which is $81,000.00 * 80/100 = $64,800.00.
She wants to withdraw 4% of her retirement savings the first year, which means she will need to have $64,800.00 / .04 = $1,620,000.00 saved.
So the answer is $1,620,000 (Second to last one)