Since f$($x$)$ has the factors x$,$

x $3,$

and

x $+6,$

then we must have

f$($x$)=$ a$($x$)($x $3)($x $+6)$

for some as yet unknown multiplier a$.$ However, since it was given that

f$(2)=80,$

we substitute $2$ for x and $80$ for

f$($x$)$

and solve

Using all the information we found, we can now write the full formula.