Question 605219
speed = distance/time


let the runner jogs to the park for t hours, with the distance of 12 miles
so the runner's speed = 12/t mph


when she jogs home at the same speed, her trip is 18 miles and her time is one hour longer:
{{{12/t=18/(t+1)}}}
12 * (t + 1) = 18 * t
12t + 12 = 18t
12 = 18t - 12t
12 = 6t
t = 12/6 = 2
the runner's speed = 12/t = 12/2 = 6 mph


so, the runner's speed is 6 miles per hour