M u lt i pl y f r a c t i o n t im es a ll d i s t an ce 4 1 ∗ 13 mi l es = 4 13 mi l es = 3 4 1 mi l es T h ey w a l k e d 3 4 1 mi l es .
You can model the situation by 13/x=1/4, where x is the distance to otter ridge. you then cross multiply, getting you to x=52