On a bright winter's day, a sports fan notices an echo as he jogs between a high school's playing field and the rear wall of its parking structure. He decides to estimate how far he stands from the reflective wall. He abruptly shouts and determines that the sound pulse returns to his as an echo 0.462 seconds later (averaging several trials for enhanced reliability). The air is a frigid −10°C.
Six months later, the sports fan decides to repeat his experiment on a hot summer day, standing at the same exact spot. This time, the echo takes a slightly shorter 0.428 seconds to return to the sports fan.

What is the temperature (in °C) of the air on the summer day?
How far (in m) does the sports fan stand from the reflective wall?