Okay so can someone tell me If i’m solving this correctly? I did x=12*6 and got 72 & then I simplified it and got 8.48 so if it’s right would 8.48 be the answer and not 72?

The formula for us in this particular incident is
[tex] 12^2=6(6+x) [/tex]
which simplifies to
144 = 36 + 6x. We combine like terms to get 6x = 108 and x = 18