Chapter 3.5, Problem 48SR

To determine

Find value of the unknown variable.

Answer to Problem 48SR

  $c=30$

Explanation of Solution

Given:

The Equation: $12=\frac{c-6}{2}$

Concept Used:

In algebra, an equation can be defined as a mathematical statement consisting of an equal symbol between two algebraic expressions that have the same value.

Calculation:

Addition or Subtraction Property of Equality:

If $\text{a}\text{=}\text{b}$ , then $\text{a}\text{+}\text{c}\text{=}\text{b}\text{+}\text{c}$ or If $\text{a}\text{=}\text{b}$ , then $\text{a}-\text{c}\text{=}\text{b}-\text{c}$

The property that states that if you add or subtract the same number to both sides of an equation, the sides remain equal (i.e., the equation continues to be true.)

Multiplication and Division Properties of Equality:

If $\text{a}\text{=}\text{b}$ , then $\text{a}·\text{c}=\text{b}·\text{c}$

If $\text{a}\text{=}\text{b}$ , then $\text{a}÷\text{c}=\text{b}÷\text{c}$ , where c is not equal to 0.

In other words, if two expressions are equal to each other and you multiply or divide (except for 0) the exact same constant to both sides, the two sides will remain equal. 

Given the Equation: $12=\frac{c-6}{2}$

  $\begin{array}{l}\text{Solve:}\\ 12=\frac{c-6}{2}\\ 2·12=2·\frac{c-6}{2}\text{[}\text{Multiply}\text{both}\text{sides}\text{by}\text{2]}\\ 24=c-6\\ 24+6=c-6+6\text{[}\text{Add}6\text{to}\text{both}\text{sides}\text{]}\\ 30=c\end{array}$   $\begin{array}{l}\text{Check}\text{the}\text{solution}\text{when}c=30\\ 12=\frac{c-6}{2}\\ 12=\frac{30-6}{2}\\ 12=\frac{24}{2}\\ 12=12(\text{checked})\end{array}$

Thus, the solution of the equation $c=30$