You don’t evaluate a function equation. The equals sign defines the function, and a function just relates two variables, so the best you can do is to show the relationship using a graph. Usually, the variable is x, which is the horizontal axis, and f(x), the function, is the vertical axis. f(x) just means “do these operations on variable x”. The vertical axis is usually labelled “y” and y is made equal to f(x).
f(x)=60+3.4(x-5)=60+3.4x-17=43+3.4x is shown below as a graph:
Every point on the sloping line is a “solution” to the function “equation”. So the point marked (5,60) is one such solution because it lies on the line. When x=5, y=f(x)=f(5)=60.