The product of a + 3 and - 2a2 + 15a + 6 is - 2a3 + xa2 + 51a + 18. What is the value of x?

A=3

B=9

C=12

D=15

(A+3) x (-2A2+15A+6) = (-2A3+XA2+51A+18)

(3+3) x (-2*3*2+15*3+6) = (-2*3*3+X * 3*2+51*3+18)

(6) x (-2*3*2=-12 + 15*3=45 + 6 = 51

(6) x (-12 + 51=39)

6 x 39 = (-2*3*3 = - 18) + x * 3*2 + (51*3+18=171)

6 x 39 - 18 + x*3*2 + 171

6 x 39 = 234

234 - 171=63

-18 + 5x=63

X = 13.5