Scaling of a rect function,drawing of signals
$f(t)$ is just time-stretched $x(t)$ by a factor of 2. Meaning $f(t)$ will take the same value at $t$, which $x(t)$ was taking at $\frac{t}{2}$. So, if the original $rect(t)$ was extending from $-1$ to $1$, then the time-stretched $rect$ will extend from $-2$ to $2$. It can not go from $-3$ to $3$. One thing to keep in mind is that all  time operations (shifting and scaling) will be applied on the independent variable $t$ in $x(t)$. So, 
$$f(t) = x(\frac{t}{2}) = (\frac{t}{2} + 2).rect(\frac{t}{4}) + 2\delta(\frac{t}{2} - 2)$$