Chapter 8.1, Problem 28IP

To determine

An equation and how many weeks Marcus will need to save

Answer to Problem 28IP

The equation as $15.75x=378$

The number of weeks is $x=24$ .

Explanation of Solution

Given:

Marcus wants to save $378 in order to buy a new electronic keyboard and he plans to save $15.75 every week from his paycheck

Concept Used:

• To get rid of a number in addition from one side, subtract the same number from both sides of equal sign.
• To get rid of a number in subtraction from one side, add the same number both sides of equal sign.
• To get rid of a number in multiplication from one side, divide the same number from both sides of equal sign.
• To get rid of a number in division from one side, multiply the same number both sides of equal sign.

Rules of Addition/ Subtraction:

• Two numbers with similar sign always get added and the resulting number will carry the similar sign.
• Two numbers with opposite signs always get subtracted and the resulting number will carry the sign of larger number.

Rules of Multiplication/ Division:

• The product/quotient of two similar sign numbers is always positive.
• The product/quotient of two numbers with opposite signs is always negative.

Calculation:

In order to find the equation, Let x weeks Marcus will need to save

Marcus want to save is $\$378$

Per week he saves is $\$15.75$

Thus, we can write an equation as $15.75x=378$

Then find the value of x as below:

  $\begin{array}{c}15.75x=378\\ \frac{15.75x}{15.75}=\frac{378}{15.75}\\ x=24\end{array}$

Thus, the number of weeks is $x=24$ .