Physics 2015 3c

Could you please help with 2015, question 3c, please?

Thank you.

Sure can help. This is a problem that requires you to remember that forces on a gradient have a vertical and a horizontal component. So calculate gravity using F = ma (in this case a is gravity). Then make a triangle using the diagram given to you in in 3a. You have one angle (12) and the vertical side of the triangle now (Fg). You are looking to calculate the gravity down the slope. As the car is stationery the gravity force down the slope is equal and opposite to the friction force up the slope.