Answer
The acceleration of A is $~~(-1.0~m/s^2)\hat{i}$
Work Step by Step
If A is moving down the incline, then the force of kinetic friction is directed up the incline.
We can find the acceleration of the two-block system:
$m_B~g - m_A~g~sin~\theta+m_A~g~\mu_k~cos~\theta = (m_a+m_B)~a$
$a = \frac{m_B~g - m_A~g~sin~\theta+m_A~g~\mu_k~cos~\theta}{m_a+m_B}$
$a = \frac{(32~N) - (102~N)~sin~40^{\circ}+(102~N)(0.25)~cos~40^{\circ}}{32~N/9.8~m/s^2+102~N/9.8~m/s^2}$
$a = -1.0~m/s^2$
The acceleration of A is $~~(-1.0~m/s^2)\hat{i}$
