Answer: The linear equation to represents the total in the checking account :
f(x) = $180-$2.5x
Explanation:
Since we have given that
Amount showing at the beginning of the month = $180
After 3 days,
Balance shown in checking balance = $172.50
So, difference in 3 days would be

Hence, the linear equation to represents the total in the checking account :
f(x) = $180-$2.5x