Part a)
here as per the situation shown we can say that the tension force at the position of applied force is given as

here
= angle of rope with horizontal

so we will have

now we can say



so the tension force in the string is 1855.2 N
Part B)
this method is better then pulling the car directly because if we pull the car directly then the force on the car is 610 N while in this case we get almost 3 times more force so it is better way to pull the car