To solve the equation \( \frac{x}{3} + 3 = 4 \), we first isolate the term containing \( x \) by subtracting 3 from both sides. This gives us \( \frac{x}{3} = 1 \). Next, we eliminate the fraction by multiplying both sides by 3, resulting in \( x = 3 \). Thus, the solution to the equation is \( x = 3 \). This process demonstrates the steps of isolating a variable and solving a linear equation.