Shanna, a calendar year and cash basis taxpayer, rents property to be used in her business from Janice. As part of the rental agreement, Shanna pays $8,400 rent on April 1, 2019, for the 12 months ending March 31, 2020. How much is Shanna's deduction for rent expense in 2019? Assume the same facts, except that the $8,400 is for 24 months' rent ending March 31, 2021. How much is Shanna's deduction for rent expense in 2019?