We are tasked with estimating the publicly held debt in 1980 and 2015, calculating how much larger the 2015 debt is compared to 1980, and expressing that difference as a percentage of the 1980 GDP.

Step 1: Find the debt in 1980 and 2015

According to the problem, the publicly held debt was:

• $698 billion in 1980.
• $18,100 billion in 2015.

Step 2: Calculate the difference in debt between 2015 and 1980

We subtract the 1980 debt from the 2015 debt to find how much larger the 2015 debt is: $\text{Difference} = 18,100 - 698 = 17,402 \text{ billion dollars}$

Thus, the 2015 publicly held debt was $17,402 billion more than the 1980 debt.

Step 3: Express the difference as a percentage of the 1980 GDP

We are given that the GDP in 1980 was $2,791 billion. To express the difference in debt as a percentage of the 1980 GDP, we use the formula: $\text{Percentage difference} = \left( \frac{17,402}{2,791} \right) \times 100$ $\text{Percentage difference} = 623.5\%$

Thus, the difference in debt between 2015 and 1980 is approximately 624% of the 1980 GDP.

Final Answer:

• The publicly held debt in 2015 was about $17,402 billion more than in 1980.
• This difference is about 624% of the 1980 GDP.

Would you like further details on any step or additional clarification?

Here are 5 related questions to expand on the topic:

1. How does the change in publicly held debt compare to the change in GDP between 1980 and 2015?
2. What factors could contribute to such a significant increase in publicly held debt over time?
3. How does the U.S. debt-to-GDP ratio in 2015 compare to that in 1980?
4. What is the significance of the publicly held debt as a percentage of GDP?
5. How does the increase in publicly held debt affect the economy and government spending?

Tip: When calculating large differences like this, it's crucial to keep track of units (billions, trillions) and check for any percentage increase relative to a baseline year to fully understand the economic impact.