Blocks A and $B,$ weighing $100$ and $300$ N $,$ respectively, are

connected by a weightless rope passing over a frictionless

massless pulley, as shown. Assume a coefficient of friction

of $0\mathrm{.}30,$ and determine the acceleration and velocity of the

system $4$ s after starting from rest.

This should be the answers:

a$=3\mathrm{.}41\frac{m}{s}2$

$v=13\mathrm{.}6\frac{m}{s}$

Please show complete solution on a paper, I will give a thumbs up surely