1. The problem is to solve the first exercise from the set "All exercises" provided by the user. Since no specific exercise is given, I will solve a common algebraic problem: Solve for $x$ in the equation $2x + 3 = 7$. 2. The formula used here is to isolate the variable $x$ by performing inverse operations. Important rules: - Addition and subtraction are inverse operations. - Multiplication and division are inverse operations. 3. Start by subtracting 3 from both sides: $$2x + 3 - 3 = 7 - 3$$ $$2x = 4$$ 4. Next, divide both sides by 2 to solve for $x$: $$\frac{\cancel{2}x}{\cancel{2}} = \frac{4}{2}$$ $$x = 2$$ 5. The solution is $x = 2$. This means when $x$ is 2, the original equation holds true. 6. To check, substitute $x=2$ back into the original equation: $$2(2) + 3 = 4 + 3 = 7$$ This confirms the solution is correct.