Call Ian's rate = R
And call the time he drove in hours ,T
So
Han drove at (R + 5) for a time of (T + 1)
And
Jan drove at (R + 10) for a time of (T + 2)
We have this equation
(R + 5) (T + 1) - RT = 70
RT + 5T + R + 5 - RT =70
5T + R = 65
R = 65 - 5T
So the distance that Ian drove = RT = (65 - 5T)(T) = 65T - 5T^2 (1)
And the distance that Jan drove = (R + 10) (T + 2) = (65 - 5T + 10) (T + 2) = (75 - 5T)(T + 2) =
75T - 5T^2 + 150 - 10T = 65T - 5T^2 + 150 (2)
Subtract (1) from (2)
65T - 5T^2 + 150 = 65T - 5T^2 = 150
So Jan drove 150 miles farther than Ian
