# 9.2.1 Finding a Word Formula

## Activity: Exchanging Currencies

### Answer

(c) Substituting 5 for “number of dollars” gives the number of euros: . This agrees with the answer in part (a).

These two examples illustrate how a word formula can be used to summarize a mathematical process such as converting units of length or currencies. Once a formula has been derived, it can then be used in other situations, both for calculations by hand or by computer—for example, for currency transactions in a bank. You will be able to practice writing your own formulas in Sections 9.4 and 9.5.

Now let's look at using formulas.

9.2 Looking for Relationships

9.3 Using Formulas