Identify the forces acting on motor vehicle in straight line motion on a horizontal surface

Friction, engine thrust, normal reaction and weight, these are the forces acting on motor when it moves in a straight line

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west