Answer:
The observed temperature was 10º Celsius or 50º Fahrenheit.
Explanation:
The traveler observed that the temperature in Fahrenheit is five times the value of the temperature in Celsius, therefore:

A Fahrenheit temperature relates to a Celsius one by the following expression:

Using the second expression on the first, we can solve for the temperature in Celsius, this is done below:

The observed temperature was 10º Celsius or 50º Fahrenheit.
Initial speed(u)=0m/s
Final speed(v)= 27m/s
Time(t)=7.6s
Use the equation of motion: v = u + at
27 = 0 + a(7.6)
27/7.6 = a
a = 3.55 m/s^2 (3 s.f)