Answer:
600 pennies
Step-by-step explanation:
to start you need to understand that 1/2=5/10 so if we start with the bank 5/10 full and she adds 120 pennies that goes up 2/10. so that means 1/10 of the bank holds 60 pennies. so to find the answer you need to multiply the 60 pennies by 10, because 10*60 would be equal to the entire bank.