Answer:
Option A. [tex]x=10\ in[/tex]
Step-by-step explanation:
we know that
The combined area of the 3 windowpanes and frame is equal to
[tex](3x+12)(x+12)=924\\ \\3x^{2}+36x+ 12x+144=924\\ \\ 3x^{2}+48x-780=0[/tex]
using a graphing tool to solve the quadratic equation
The solution is [tex]x=10\ in[/tex]
see the attached figure