Answer:
1800 = 1950 - m
Explanation:
Lets call the fixed amount he withdraws every month m. He starts with $1950 and withdraws a certain amount, m, every month. At the end of the first month, he has withdrawn 1m amount of money and ends up with $1800. Therefore, 1950 - 1m = 1800. We can get rid of the 1 and get 1950 - m = 1800, or 1800 = 1950 - m. If the answer choices do not have "m" as a variable, you can substitute "m" for any variable.