Age Problem: Lisa and her brother

easyGrade 3-5age difference

The Problem

Lisa is 23 years old. Her brother is 7 years younger than Lisa. How old is her brother?

Answer:

16 years old

Key Information

  • Lisa is 23 years old
  • her brother is 7 years younger

Step-by-Step Solution

1

Identify the given information

Lisa's age = 23 years, Age difference = 7 years
2

Set up the equation

her brother's age = Lisa's age - 7
3

Substitute values

her brother's age = 23 - 7
4

Calculate

23 - 7 = 16
5

Final answer

her brother is 16 years old

Common Mistakes to Avoid

  • Adding instead of subtracting the age difference
  • Confusing who is older or younger

Helpful Tips

  • Read the problem carefully to identify who is older
  • Subtract when someone is younger, add when they are older

Real-World Application

Age problems help understand relationships between ages and develop subtraction skills.

Related Topics:

agesubtractionword problemsbasic math

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