Question

Which sentence BEST describes what operation should be performed to solve the equation -2j = 15?

Answer 1

Division by -2

Explanation:

The properties of equality allow us to manipulate equations in order to solve for a variable.

Properties of Equality

The properties of equality, also referred to as PoEs, describe how an equation can be changed while remaining true. There are numerous PoEs such as the reflexive, substitution, and addition properties of equality. However, for the purposes of this question, the most important is the division property of equality. The division property of equality states that if both sides of an equation are divided by the same number, the equation is still true. In other terms:

• if a = b, then
  `\displaystyle(a)/(c) =(b)/(c)`

Solving for a Variable

To find an unknown variable, we need to isolate the variable. This means using the properties of equality and other techniques to get the variable all by itself on one side of the equation. To isolate j, we need to divide both sides of the equation by -2. This will isolate j and maintain equality as shown by the division property of equality.

• 
  `(-2j)/(-2)= (15)/(-2)`
• j =
  `-(15)/(2)`

By dividing both sides by -2, we can see that j = -15/2.