Answer:
35,000 feet
Explanation:
So t is the atmospheric temperature
g is the ground temperature
First sub in the values that you know
t = -65.5 and g = 57
-65.5 = -0.0035a + 57
Rearrange: to make 'a' on its own
-65.5 - 57 = -0.0035a
-122.5/-0.0035 = a
Use a calculator
a = 35,000 ft