Show that Pacioli’s answer is incorrect. What was he thinking of in presenting his rule?

12.     . The equation 6x3 = 43x2 + 79x + 30 is solved in the
Summa of Luca Pacioli as follows: “Add the number to
the cose to form a number, and then you get one cubo equal
to 7 1 censi plus 18 1 , after you have reduced to one cubo 66
[divided all the terms by 6]. Then divide the censi in half
and multiply this half by itself, and add it onto the number.
It will be 31 1   and the cosa is equal to the root of this plus 7 144 38
3 12 , which is half of censi.”   Show that Pacioli’s answer is incorrect. What was he thinking of in presenting his rule?