Solve for D (f^3-M)D=n

$(f^{3} - M) D = n$

Divide each term in $(f^{3} - M) D = n$ by $f^{3} - M$ .

$\frac{(f^{3} - M) D}{f^{3} - M} = \frac{n}{f^{3} - M}$

Simplify the left side.

Cancel the common factor of $f^{3} - M$ .

Cancel the common factor.

$\frac{(f^{3} - M) D}{f^{3} - M} = \frac{n}{f^{3} - M}$

Divide $D$ by $1$ .

$D = \frac{n}{f^{3} - M}$