To represent the problem in the form \( px + q = r \), we start with the initial amount Maria has, which is $50, and then add the amount she saves each week.
Let's denote:
- \( x \) as the number of weeks,
- The initial amount in her account is $50,
- She saves $19 each week, which means after \( x \) weeks, she will have saved \( 19x \).
The total amount in her account after \( x \) weeks can be expressed as:
\[ 50 + 19x \]
We want this total to equal $259:
\[ 50 + 19x = 259 \]
This fits the form \( px + q = r \) where:
- \( p = 19 \),
- \( q = 50 \),
- \( r = 259 \).
Therefore, the correct equation is:
19x + 50 = 259.