Explanation:
he ran 3 times as fast.
speed = distance/time
speed × time = distance
time = distance/speed
x = speed of the challenger = x miles/hour
y = time for 32 miles = 32/x
speed of Archimedes = 3x miles/hour.
y - 3 = 60/3x
using the first in the second equation
32/x - 3 = 60/3x
let's multiply both sides by 3x
3×32 - 9x = 60
96 - 9x = 60
-9x = -36
x = 4
so, the challenger ran 4 mph (in other words : he more or less walked a little bit faster),
Archimedes ran 4×3 = 12 mph.