Finding friction and acceleration for a 3.5kg box pushed at 40 degrees

[suspenc3]

A 3.5 kg box is pushed along a horizontal floor by a force F of magnitude 15N at an angle of 40degrees below the horizontal. The coefficient of kinetic friction is 0.25. Calculate the magnitude of the frictional force on the block from the floor and the acceleration of the block.

I don't really know where to start.

Can anyone Help?

 

[Tide]

The sum of all the forces acting on the block equals the mass of the block times acceleration. You just need to account for all the forces properly.

 

[Integral]

Start exacty where you start with all problems of this nature. With a free body diagram. Draw your forces and the components. Sum the componts and procede.

Show us your work.