How?
* Substitution (you're given all the values you need to completely fill in all quantities on the right hand side of the equation).
* Simplification of RHS.
* Calculation of RHS. The loan amount (the left hand side of the equation) equals the the right hand side, and when the right-hand side is evaluated using the given values, it will give you precisely what the loan amount is equal to.
$$\text{Loan amount}\; = \dfrac{\text{Monthly Payment}}{\left(1 + \dfrac{\text{Interest rate per annum}}{100}\right)^{\large \text{(Term of loan)}}} \times \text{Term of loan} \times 12 $$
$$\text{Loan amount}\; = \dfrac{3049.40}{\left(1 + \dfrac{1.09}{100}\right)^{30}} \times 30 \times 12$$ $$= 3049.4\times (1.0109)^{-30} \times 360 \approx 792996.01$$