Hi Lezly,
This zombie goes 3 m/s for 24 seconds. . . I've never seen a zombie walk that fast but I guess he ate his Wheaties.
Remember the formula distance = rate x time
So Distance = 3 x 24 = 72 meters.
He is 50 meters away from the group, so he must have been 22 meters away when he started (72 - 50).
Dan