How do you make [n] the subject of the formula?

The parabola opens: y=√x-4 (principal square root) up down right left

Me solve this problem, and someone clearly explain to me how to solve it.1.) use the value of the discriminant to determine if the given trinomials has 2 real solutions, 1 real solution, or no real solutions. a.  x2  − 4x  − 7 = 0b. 4r2  + 11r  − 3 = 0c. 3m2  + 7 = 0d.  t2  + 2t  + 1 = 0

The length of a rectangular piece of land is 92 yards more than three times its width. the perimeter is 760 yards. find its dimensions.