When you need to solve a word problem, you should:

- Read the problem.
- Write down all the information that the problem gives you.
- Write down what the question is asking you to do.
- Use clue words in the problem to make a plan to solve the problem.
- Write your plan as an equation.

In this section we will cover one of the most important steps in problem solving. Whenever you get an answer to a problem, you should think about what the answer means and whether or not it is reasonable. Ask yourself:

**Based on the problem I just solved, doe****s my answer make sense?**

Johnny is 24 years younger than his dad. If Johnny's dad is currently 30 years old, how old is Johnny?

Attempted Solution:

Given: Johnny's dad is 30

Question: How old is Johnny?

Plan: I should subtract 24 from Johnny's dad's age to find Johnny's age

Equation: J = 30 – 24

Calculator:

*Modified from: SharpEl-5120, EpiVictor, Wikimedia Commons*

Answer: J = -21

- Is this answer reasonable?
- Why or why not?
- Can you find where the mistake happened?

The first factor to consider is whether or not the answer to the problem is physically possible.