Under her cell phone plan, Ximena pays a flat cost of $44.50 per month and $4 per gigabyte. She wants to keep her bill at $50.10 per month. How many gigabytes of data can she use while staying within her budget?
Let the number of gigabytes of data she can use be represented by $x$.
So the equation representing the total cost of her bill is $44.50 + 4x = 50.10$.
Subtracting $44.50$ from both sides gives $4x = 5.60$.
Dividing both sides by $4$ gives $x = \boxed{1.40}$. Answer: \boxed{1.40}.