Problem # $3$: $(25$ points$)$

Use the unit load method to determine the deflection ${}_A$ at the left end $A$ of the following beam. The beam is made of reinforced concrete with modulus $E=3,600\frac{k}{i}{n}^2$ and it has an $8-$in $12-$in rectangular cross$-$section with a moment of inertia $I=1,152i{n}^4.$