When constructing the walls of a home, several layers of materials are used. Read the following problem. Derive and solve the indicated mathematical formula. Determine the total R-value of this wall using the chart below. When a range is given for R-value, assume the highest value given.
Subtraction is usually the second of the basic mathematical functions learned.
Any problem that asks for the difference between two quantities is a subtraction problem. You are probably familiar with subtraction problems given in column format, as seen in Example 2. Zeros may be added to the right of the decimal if you wish to have all columns filled. Subtraction could also be used by the builder installing insulation into a new or existing home. Perhaps the builder was working on an existing home and wanted the insulation in the attic to have an R-value of 30.