Answer:
Bernie left home riding his bike at a rate of 15 mph.
Charlie left one hour later biking at a rate of 20 mph.
Bernie distance = 15*t (time is represented by t)
Charlie distance = 20*(t-1) (he left after 1 hour)
15t = 20t - 20
-5t = -20
t = 4
4*15 = 60
when t = 3 hours
3*20 = 60
