1. Solve for $x$: $$2x + 3 = 7$$ 2. Factor the quadratic expression: $$x^2 - 5x + 6$$ 3. Simplify the expression: $$\frac{3x^2 - 6x}{3x}$$ 4. Find the value of $y$ when $$y = 2x^2 - 4x + 1$$ and $x = 3$ 5. Solve the system of equations: $$\begin{cases} 2x + y = 5 \\ x - y = 1 \end{cases}$$