Let the temperature on the first day of summer in 2001 be \( T \) degrees Fahrenheit. According to the information provided:
The temperature in 2002 was 96 degrees Fahrenheit, and this was 3 degrees less than the temperature in 2001. We can express this relationship with the equation:
\[ T - 3 = 96 \]
To find \( T \), we can add 3 to both sides of the equation:
\[ T = 96 + 3 \]
\[ T = 99 \]
Thus, the temperature on the first day of summer in 2001 was 99 degrees Fahrenheit.