Charmaine's penny bank is

1/10

full. After she adds

400

pennies, it is

1/2

full. How many pennies can Charmaine's bank hold

We shall take X as the total amount of cash her piggy bank can hold

therefore 1x/10+400=1x/2

400=1x/2-1x/10

we should make the denominator's the same

400=5x/10-1x/10

400=4x/10

400*10=4x

4000=4x

4000/4=X

1000=X

hope u found this useful