Using a rope to pull a box across a floor (problem with friction)

[studentgrade12]

Homework Statement:

A rope exerts a force of magnitude 12N, at an angle 31 degrees above the horizontal on a box at rest. the coefficients of friction between the box and the floor are 0.55 and 0.50. The box remains at rest, determine the smallest possible mass of the box.

Relevant Equations:

F = ma
coefficient of friction = force/force of normal

I have been trying a couple of problems with forces and i am not getting the answer, I don't understand what i am doing wrong. Can someone please guide me through this question

 

[kuruman]

We cannot explain to you what you are doing wrong if you don't show us what you tried. Please post your attempt(s) to help us help you.

 

[haruspex]

Usual error for such a problem is failure to consider the balance of forces vertically.