Multiplying f(x) by 1/2 meant that the function is being compressed by a factor of 1/2. This means that the function gets closer to the x-axis.
Based on the graph, the slope of the linear function is -1/2. See the illustration below to see why.
If we multiply the slope -1/2 by the factor 1/2, the slope changes to -1/4.
Also, the y-intercept that is at y = -3 after multiplying by a factor of 1/2, the y-intercept changes to -1.5.
Hence, the graph of y = 1/2f(x) will have a y-intercept at y = -1.5 and has a slope of -1/4. The graph of y = 1/2f(x) is shown below. (blue line)
