M1 resolving forces help?!?!

I don't understand the second part of question 15. I worked out that the coefficient of friction is 0.183 but I can't work out the acceleration??
P.s. The answer is 3.34 but I'm not sure how to get there

Resolve down the plane to find the resultant force down the plane then equate that to ma, since F = ma. Then a = F/m.

But what are they? When I work out the forces acting down the plane (6gsin20+ 10cos20) and minus it from the frictional force (0.183*6gcos20) and plug it into f=ma, I get the wrong answer?

So you're saying the reaction force is $6g \cos 20$? I assumed you resolved perpendicular to the plane, but you forgot to factor in the perpendicular to the plane component of the 10 N force.

Oh, I didn't realise you had to account for the perpendicular forces- I've only worked out the parallel forces. So the perpendicular of the block would be 6gcos20 but what would the perpendicular component be for the 10N force? Do both these forces act down the plane?
Thanks