First month account balance changed = $55.
Next month account balance changed = $67.
We can clearly see that $67 is the larger amount than $55.
In order to find, how much more amount is in second month, we could find the difference of those amounts of each month.
Second month balance changed - First month account balance changed.
$67 - $55 = $12.
So, we can say that first month account balance changed represents the $12 lesser change by second month.