1. The problem is to solve the equation for $x$: $$3x + 5 = 20$$ 2. The formula used here is to isolate $x$ by performing inverse operations. We want to get $x$ alone on one side of the equation. 3. First, subtract 5 from both sides to cancel the +5 on the left: $$3x + 5 - 5 = 20 - 5$$ $$3x = 15$$ 4. Next, divide both sides by 3 to solve for $x$: $$\frac{3x}{\cancel{3}} = \frac{15}{\cancel{3}}$$ $$x = 5$$ 5. So, the solution is $x = 5$. This means if you replace $x$ with 5 in the original equation, both sides will be equal. 6. To check: $$3(5) + 5 = 15 + 5 = 20$$ which matches the right side. Therefore, the answer is $x = 5$.