1. Problem: Solve $2x + 3 = 7$. Step 1: Subtract 3 from both sides: $2x = 4$. Step 2: Divide both sides by 2: $x = 2$. This problem is correct. 2. Problem: Simplify $\frac{4}{2} + 3$. Step 1: Simplify the fraction: $2 + 3$. Step 2: Add: $5$. This problem is correct. 3. Problem: Solve $x^2 = -1$ over real numbers. Step 1: Recognize no real solution since $x^2$ cannot be negative. This problem is correct but has no real solution. 4. Problem: Simplify $5 - 2 \times 3$. Step 1: Multiply first: $5 - 6$. Step 2: Subtract: $-1$. This problem is correct. 5. Problem: Solve $\frac{1}{x} = 0$. Step 1: Recognize no solution since $\frac{1}{x}$ cannot be zero. This problem is correct but has no solution.