Based on the images and Correct each statement making it negative

corras is the only one that is informal but doesn't follow the suffix rule. correr is the verb. corre is the formal verb form. corra would be used as the formal is corre ended with an a.

your best bet would be corras, it's the only one that is informal but is still wrong

yo nos habíamos enterado de que los precios de los tiquetes subieron.

btw its yo not ya, ya means already yo means me or in this case us.