What are the zeros of the equation x^2+4x-12=0

Given: △abc, ab=15, bd=9 ad ⊥ bc , m∠c=30°. find: the perimeter of the triangle.

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expressions 4s +9s represents the total number of items that will be displayed on s shelves. simplify this expression

Which ordered pair (c,d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15