Economic growth Rule of 70 and the p-o-w-e-r of compounding

In 2019 America's real GDP was $20 trillion and Floridastan, just south of the U.S., had a real GDP of $5 trillion. The U.S. has an average annual growth rate of real GDP equal to 3.5% while Floridastan has an average annual growth rate of real GDP equal to 7%.

MUST show calculations for a, b, c, and d to receive credit

a. America's real GDP will double in about __________ years.

b. Floridastan's real GDP will double in about __________ years.

c. After 40 years, the U.S. will have a real GDP equal to $__________ trillion.

d. After 40 years, Floridastan will have a real GDP equal to $__________ trillion.