**Introduction to Linear Equations Given as Formulas**

At times math students are given a formula like *I* = *Prt* and asked to solve for one of the variables; that is, to isolate that particular variable on one side of the equation. In *I* = *Prt* , the equation is solved for “ *I* .” The method used above for solving for *x* works on these, too. Many people are confused by the presence of multiple variables. The trick is to think of the variable for which you are trying to solve as *x* and all of the other variables as fixed numbers. For instance, if you were asked to solve for *r* in *I* = *Prt* , think of how you would solve something of the same form with numbers, say

The steps for solving for *r* in *I* = *Prt* are identical.

All of the formulas used in the following examples and practice problems are formulas used in business, science, and mathematics.

**Examples**

#### Examle 1:

Solve for q.

**Example 2:**

Solve for *m* .

**Example 3: **

Solve for C.

**Example 4:**

Solve for *b* .

**Linear Equatinos Given as Formulas Practice Problems**

**Practice**

Solve for indicated variable.

4. *P* = 2 *L* + 2 *W* ; *L*

5. *L* = *L* _{0} [1 + *a* ( *dt* ); *a*

6. *S* = C + RC; C

7. *A* = P + PRT; R

9. *L* = *a* +( *n* – 1) *d; n*

**Solutions**

Practice problems for these concepts can be found at: Algebra Linear Equations Practice Test.

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