Tammy’s bank can hold a total of 840 pennies. The bank was already 1/2 full. 1/2 is equivalent to 3/6. When 280 pennies were added, it added 2/6 the capacity of pennies. This is equivalent to 1/3. Therefore, you can multiply the 280 pennies by 3 to find the total capacity, which is 840 pennies.