To evaluate expressions, we substitute values for the variables in the expression.  Then, using the correct order of operations, simplify the expression to a single value.

Example:  Evaluate 5h + 5f for h = 3 and f = 2.

            5 (3) + 5 (2) = 15 + 10 = 25

            Be sure to use correct order of operations!

Additional examples:

Campground charges $7 per night, what is the cost for 6 days?

                        Let n = the number of nights

                                    7n = 7(6) = $42

            Evaluate c - 1.25         when c = 17.5

                                    c - 1.25 = 17.5 - 1.25 = 16.25

You are taking a fifty-mile hike.  How many miles remain when you have hiked 25 miles?

Let m = the number of miles remaining

The expression is 50 - m

50 – 25 is 25 miles

What if you have hiked 40 miles?

50 – 40 is 10 miles

What if you have hiked 5 miles?

50 – 5 is 45 miles

What if you have hiked 12.5 miles? 

50 – 12.5 is 37.5 miles