Final answer:
The United States could run on the energy released by a 10²º J solar flare for approximately 3 months.
Step-by-step explanation:
To calculate how many years the United States could run on the energy released by a 10²º J solar flare, we need to divide the energy consumed by the United States in a year (2.5 × 10¹⁹ J) by the energy released by the solar flare (10²⁰ J).
Using this calculation:
Years = (Energy consumed by the United States)/(Energy released by the solar flare)
Plugging in the values:
Years = (2.5 × 10¹⁹ J)/(10²⁰ J)
Years = 0.25 years or approximately 3 months.