SOMEONE, PLEASE HELP ME 20 POINTS HELP

If x=-3 is the only x-intercept of the graph of a quadratic equation, which statement best discribes the discriminant of the equation?

You paid 28.00 for 8 gallons of gasoline. how much would you pay for 15 gallons of gasoline?

Pyotr tchaikovsky sporting goods operates on a 45% overhead based on the selling price, which results in an overhead of $65.34 on the newest version of an air hockey game set. if the air hockey game set costs pyotr tchaikovsky sports $49.32, find the selling price, the markup, and the net profit.