Many of the situations that are modeled by equations are more complex and require two or more operations.

You may need to add the total price of several items at the store and then multiply to calculate the sales tax.

You may need to multiply to figure how much allowance you earn in 6 weeks, and then subtract because you bought something you want.

You may need to multiply by a percent and then subtract to find the sale price of something you want to buy.

No matter what the reason, you will often need more than one operation in the same problem. When this happens follow these five steps.

  1. Read the problem.
  2. Write down all the information that the question gives you.
  3. Write down what the problem is asking you to do.
  4. Use the clue words that you learned in sections 1-4 of this lesson to make a plan to solve the problem.
  5. Write your plan as an equation.

As you write your equation, remember the rules of the order of operations represented by the acronym: Click on each letter for a reminder of what it means.

Interactive exercise. Assistance may be required.

The rules for simplifying expressions include the following:

  1. Evaluate operations that are in parenthesis or other grouping symbols.
  2. Evaluate exponents.
  3. Multiply or divide, moving from left to right.
  4. Add or subtract, moving from left to right.

A lot of people remember the acronym PEMDAS by remembering the phrase:

Remember, if your plan requires you to add or subtract numbers BEFORE doing multiplication or division, use parentheses to make the addition or subtraction happen first.

Interactive exercise. Assistance may be required.