Sofia's driving speed, given the relationship between the walking and driving speed is 50 km / h.
How to find the driving speed?
For the driving part, the time spent driving is D / Vd. For the walking part, the time spent walking is W / Vw.
Given that the speed of driving is 15 times her walking speed, we can express Vd in terms of Vw as follows:
Vd = 15Vw
Set up the equations for time:
Time driving + Time walking = Total time
(D / Vd) + (W / Vw) = T
We have values for D, W, and T:
D = 45 km
W = 2 km
T = 1.5 hours
Express Vd in terms of Vw and substitute the known values:
(45 / 15Vw) + (2 / Vw) = 1.5
(3 / Vw) + (2 / Vw) = 1.5
(5 / Vw) = 1.5
Now, solve for Vw:
Vw = 5 / (1.5)
Vw = 10/3 km/h
Now that we have found Sofia's walking speed (Vw), we can find her driving speed (Vd) using the relationship given earlier:
Vd = 15Vw
Vd = 15 * (10/3)
Vd = 50 km/h