Solve for D fD-7=q^2

$f D - 7 = q^{2}$

Add $7$ to both sides of the equation.

$f D = q^{2} + 7$

Divide each term in $f D = q^{2} + 7$ by $f$ and simplify.

Divide each term in $f D = q^{2} + 7$ by $f$ .

$\frac{f D}{f} = \frac{q^{2}}{f} + \frac{7}{f}$

Simplify the left side.

Cancel the common factor of $f$ .

Cancel the common factor.

$\frac{f D}{f} = \frac{q^{2}}{f} + \frac{7}{f}$

Divide $D$ by $1$ .

$D = \frac{q^{2}}{f} + \frac{7}{f}$