This was not just easy, it was Dan Quayle easy, so my grading was easy.

The easiest solution: **Step 1**. equation of characteristics:

$$

\frac{dx}{3}=\frac{dt}{2}\implies x-\frac{3}{2}t =C \implies u=f(x-\frac{3}{2}t)

$$

is a general solution. Other equivalent forms are possible leading to the same final answer, but this one is the most natural and straightforward.

**Step 2** Initial condition: $u(x,0)=f(x)=\sin(x)$ and therefore

$$

\boxed{u(x,t)=\sin(x-\frac{3}{2}t)}.

$$

Several students put the wrong sign $u=\sin(x+\frac{3}{2}t)$, several made mistakes on Step 2 and got marks halved. Few made really grave mistakes like trying method of separation, but majority did well and got all 20 (correct but ugly solutions/answers are not punished).