Final answer:
Joan had approximately $2400 in the bank one year ago.
Step-by-step explanation:
To find out how much money Joan had in the bank one year ago, we need to consider that she has 5% more money now than she had one year ago. Let's say she had a certain amount of money x in the bank one year ago. According to the given information, she now has $2,520 in the bank, which is 5% more than what she had one year ago. So we can set up the equation:
x + 0.05x = 2520
Combining like terms, we get:
1.05x = 2520
To solve for x, divide both sides of the equation by 1.05:
x = 2520 ÷ 1.05
Calculating this value, we find that Joan had approximately $2400 in the bank one year ago.