Final answer:
The student's question can be solved by subtracting the total value of Hannah's nickels from the total value in her piggy bank. The equation representing the amount of dimes that Hannah has in standard form is 10D = 450, establishing that each of Hannah's dimes contributes 10 cents to her total sum of 450 cents.
Step-by-step explanation:
In the question, Hannah has a piggy bank containing a total of $7.80 solely in nickels and dimes. A nickel is worth 5 cents while a dime is worth 10 cents. If Hannah has 66 nickels, then the value of her nickels is 66 * 0.05 = $3.30.
So, the remainder of the money, which is in dimes, is $7.80 - $3.30 = $4.50. In standard form, an equation representing the amount of dimes (D) that Hannah has can be written as: 0.10D = 4.50 or, to eliminate decimals and make the equation integers, 10D = 450 could be the answer. This standard form equation means for every dime Hannah has, it contributes 10 cents to the total amount of money she has, which is 450 cents.
Learn more about Standard form equation