Bernie left home riding his bike at a rate of 15 mph Charlie left one hour later biking at a rate of 20 mph how long will it take Charlie to catch up with Bernie

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