<h2>
Systems of Equations Word Problems</h2>
To solve systems of equations word problems, we can delegate certain variables to subjects mentioned in the word problem. From there, we can form equations based on the given values.
<h2>Solving the Question</h2>
Let <em>a</em> be the older sibling's age and <em>b</em> be the younger sibling's age.
We're given:
- <em>a</em> + <em>b</em> = 55 years old
- <em>b</em> + 9 years = <em>a</em>
<em />
All we've done so far is translate the given sentences into equations. Now, we have to solve for <em>b</em>, which is the age of the youngest sibling. Solve using substitution:

Therefore, the younger sibling is 23 years old.
<h2>Answer</h2>
23 years old.