Courtney, this is way simpler than it seems. Let's think about it.
If she drives 58 mph to get there, it takes 1 hour. If she drives 58 - 29 = 29 mph, it takes 2 hours, one hour longer.
To solve algebraically, since distance = rate x time and the distance each way is the same...
1t = 2(t -29)
t = 2t - 58
-t = -58
t = 58
Hope this helps!