How do you write an equation of a parabola with a vertex at the origin and a directrix at y = 5?

Volume of a cylinder with a radius of 13 in and height of 30 in

Evaluate the expression for the given value of the variable 7a - 4a for a =8

Three numbers x, y, and z are in the ratio 2: 7: 8. if 12 is subtracted from y, then three numbers form a geometric sequence (in the order x, y–12, z). find x, y, and z. there are 2 sets.