Final answer:
Marla's bank can hold 1600 pennies.
Step-by-step explanation:
To find out how many pennies Marla's bank can hold, we need to determine the total capacity of the bank.
Given that the bank is 2/5 full initially and then becomes 2/3 full after adding 320 pennies, we can set up the following equation:
2/5 x Total capacity + 320 = 2/3 x Total capacity
To solve for the total capacity, we can cross-multiply:
2/5 x Total capacity = 2/3 x Total capacity - 320
1/5 x Total capacity = 320
Total capacity = 320 x 5 = 1600
Therefore, Marla's bank can hold 1600 pennies.