3x^2+4x-27=2x^2+5x-15
3x^2+4x-27-2x^2-5x+15=0
x^2-x-12=0
D=1-4*1*(-12)=1+48=49
x1=1-7/2=-6/2=-3
x2=1+7/2=8/2=4