What does this equal -1/2x+9=-10

answer: the angel abc is 30°,and the abc is a triangle where the angel bac is 90°

so ac is the half of 24=12ft,and from the pythagorean theorem we find ba

ba=√bc^2-ac^2=√576-144=√432=12√3ft

so bac is 12+12√3=12(1+√3)ft

add a picture or measurements so i cab

i may be incorrect but i believe that her first error was in step one when she multiplyed her equation by 1/4 when she should have divided it by 1/4