Is mno pqr if so name the congruence postulate that applies

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

Determine the number of girls in a math class with 87 boys if there are 25 girls for every 75 boys

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