Calculate Frictional Forces Needed for 6.5kg Shopping Cart on 13° Incline

[wind522]

I have a question..

A shopper pushes a 6.5kg shopping cart up a 13 degree incline, heading east. Find the magnitude of the horizontal force, F, needed to give the cart an acceleration of 1.61 m/s2 (seconds squared).

This is what I have done.
sigmaFx= F(what I'm trying to find) - Fg,x - Ff
MAnet = F - mgsin(theta) - u(mieu)Fn
F = MAnet + mgsin(theta) + uFn
F = (6.5kg)(1.61m/s2) + (6.5kg)(9.81m/s2)sin13 +u(63.13070718N)
And here's where I'm stuck because there's two variables. Does anyone know what I'm doing wrong?

The answer should be in Newtons

 

[Doc Al]

Are you supposed to be including friction? If so, you'll need the coefficient of friction.

Also, note that the applied force is horizontal, thus if you are finding components parallel to the incline you must take that into account.