To evaluate an expression at a given value means that you substitute the given value anywhere you see the variable. For example, if the expression is:

and the problem asks you to evaluate the expression at x=9, then we substitute x=9 and get:

Now, question number 3 asks us to evaluate

at t=13.5, u=7, and v=6. Therefore substituting the given values we get:

Answer: 104.51