Answer:
let us assume that the distance from Ottawa at which they meet each other is 'x' km. Then the time it took For Erika to travel this distance is:
t_Erika = x/80
kareem started 1 hour after Erika. So the time it took for Kareem to cover that 'x' distance is (including the 1 hour delay time):
t_Kareem = 1 + x/100
These two times must be equal to each other since they meet at this point of time. Setting them equal and solving for x:
t_Erika = t_Kareem
x/80 = 1 + x/100
x/80 - x/100 = 1
5x/400 - 4x/400 = 1
(5x-4x)/400 = 1
x/400 = 1
x = 400 km
