1. We start with the expression inside the brackets from step 3, which we denote as $\left(\frac{a}{b} + c\right)$. 2. According to your request, we rewrite this expression as a fraction with numerator 1, so it becomes $\frac{1}{\frac{b}{a} + \frac{1}{c}}$. 3. Next, we square this entire fraction, resulting in $$\left(\frac{1}{\frac{b}{a} + \frac{1}{c}}\right)^2.$$ 4. This means the original bracketed expression is now transformed into the square of the reciprocal of the sum inside the brackets. 5. This manipulation is useful in algebra when simplifying complex fractions or expressions involving powers. 6. The final expression is $$\left(\frac{1}{\frac{b}{a} + \frac{1}{c}}\right)^2.$$