Example 2.26 from Elementary Algebra, 2.2 Solve Equations using the Division and Multiplication Properties of Equality

Solve Equations using the Division and Multiplication Properties of Equality: example 2.26

Andreas bought a used car for $12,000. Because the car was 4-years old, its price was $\frac{3}{4}$ of the original price, when the car was new. What was the original price of the car?

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Translate and solve:

The annual property tax on the Mehta’s house is $1,800, calculated as $\frac{15}{1,000}$ of the assessed value of the house. What is the assessed value of the Mehta’s house?

How did it go?

What are you asked to find?	The original price of the car
Assign a variable.	Let $p$ = the original price.
Write a sentence that gives the information to find it.	$12,000 is $\frac{3}{4}$ of the original price.
Translate into an equation.	$12,000 = \frac{3}{4} p$
Solve.	$\begin{matrix} \frac{4}{3} (12,000) = \frac{4}{3} \cdot \frac{3}{4} p \\ 16,000 = p \end{matrix}$
	The original cost of the car was $16,000.
Check: Is $\frac{3}{4}$ of $16,000 equal to $12,000? $\begin{matrix} \frac{3}{4} \cdot 16,000 & \overset{?}{=} & 12,000 \\ 12,000 & = & 12,000 ✓ \end{matrix}$

What are you asked to find?	The original price of the car
Assign a variable.	Let $p$ = the original price.
Write a sentence that gives the information to find it.	$12,000 is $\frac{3}{4}$ of the original price.
Translate into an equation.	$12,000 = \frac{3}{4} p$
Solve.	$\begin{matrix} \frac{4}{3} (12,000) = \frac{4}{3} \cdot \frac{3}{4} p \\ 16,000 = p \end{matrix}$
	The original cost of the car was $16,000.
Check: Is $\frac{3}{4}$ of $16,000 equal to $12,000? $\begin{matrix} \frac{3}{4} \cdot 16,000 & \overset{?}{=} & 12,000 \\ 12,000 & = & 12,000 ✓ \end{matrix}$

Solve Equations using the Division and Multiplication Properties of Equality: example 2.26

Solution

Your turn

Solve Equations using the Division and Multiplication Properties of Equality: example 2.26

Solution

Your turn