Dose anyone know how to do this ? ?

Evaluate the discriminant of each equation. tell how many solutions each equation has and whether the solutions are real or imaginary. x^2 - 4x - 5 = 0

Alex took his brother to a birthday party. the party was scheduled to last for 1 and 3/4 hours but they stayed for 4/5 of an hour more. how long did she stay at the party?

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?