(30-9x)(9x+3)=252
9(10-3x)(3x+1)=252
(10-3x)(3x+1)=28
-9x^2+27x+10=28
9x^2-27x+18=0
x^2-3x+2=0
(x-2)(x-1)=0
x1=2x2=1