The function R(x)=-3tan(1/2x) is a reflection about the x-axis, since the coefficient of the tangent function is negative.
The vertical stretch factor is 3, since it is the absolute value of the coefficient (-3) outside of the tangent function.
The horizontal stretch factor is 2, since it is the coefficient of x inside the tangent function, multiplied by 1/2.
The period is pi, since it is the distance between consecutive vertical asymptotes of the tangent function. This can be found by setting 1/2x equal to (n+1/2)pi or (n-1/2)pi, and solving for x, where n is an integer. The difference between these two values of x gives the period.