Here, m=10kg
The resultant force acting on the body is F=(8N)2+(6N)2=10N
Let the resultant force F makes an angle θ w.r.t. 8N force.
From figure, tanθ=8N6N=43
The resultant acceleration of the body is a=mF=10kg10N=1ms−2
The resultant acceleration is along the direction of the resultant force.
Hence, the resultant acceleration of the body is 1ms−2 at an angle of tan−1(43) w.r.t. 8N force.