Let y=f(x). Therefore, y=(1/2)x-5 which is a line of slope 1/2 and y-intercept of -5. The inverse function of this equation will also be a line. We find this by switching the x & y then solve for y:
y=(1/2)x-5 original equation
x=(1/2)y-5 switch x & y
x+5=(1/2)y isolate the y term by adding 5 to each side
2(x+5)=y multiply both sides by 2 to isolate y
2x+5=y the inverse function
The inverse function is a line with slope of 2 and y-intercept of 5. If you were to plot both functions on the same graph you would see that the 2 functions are symmetrical about the line y=x.