1. Solve for $x$ in the equation $5x - 15y = 20$. Step 1: Start with the equation: $$5x - 15y = 20$$ Step 2: Add $15y$ to both sides to isolate terms with $x$: $$5x - 15y + 15y = 20 + 15y$$ $$5x = 20 + 15y$$ Step 3: Divide both sides by 5 to solve for $x$: $$x = \frac{20 + 15y}{5}$$ Step 4: Simplify the fraction by dividing numerator terms by 5: $$x = \frac{\cancel{20}^4 + \cancel{15}^3 y}{\cancel{5}}$$ $$x = 4 + 3y$$ Final answer: $$x = 4 + 3y$$