Initial amount in Elaine's account = m dollars ---- (1)
On December 8, total money deposited by Elaine = 1200 + r + 568.9
= r + 1768.9 ----- (2)
Total money on her account now = m + r + 1768.9
Total money she cashed by cheques = t + 73.7.
Therefore, her current balance in her account = (m + r + 1768.9) - (t + 73.7)
= (m + r - t) + 1695.2.
Hence, the algebraic expression that represents the amount of money in her account after the transactions is (m + r - t) + 1695.2.