For this case we have:
We define the following variable
x : Speed of the car in South direction
By definition, we know that:
[tex]Distance = Speed * Time[/tex]
For the car in north direction:
[tex]D1 = V1 * T1\\D1 = 50mph * 3h\\D1 = 150 miles[/tex]
For the car in south direction:
[tex]D2 = V2 * T2\\D2 = x * 3\\D2 = 3x[/tex]
The distance between both cars, after 3 hours, is:
[tex]D = D1 + D2[/tex]
So, we have:
[tex]345 = 150 + 3x[/tex]
Clearing x;
[tex]3x = 345-150\\3x = 195\\x = 65[/tex]
Thus, the speed of the car in the south direction is [tex]x = 65mph[/tex]
Answer:
Option B
