1. **State the problem:** Solve the equation $3(2x+5)=39$ for $x$. 2. **Use the distributive property:** Multiply 3 by each term inside the parentheses. $$3 \times 2x + 3 \times 5 = 6x + 15$$ So the equation becomes: $$6x + 15 = 39$$ 3. **Isolate the variable term:** Subtract 15 from both sides. $$6x + 15 - 15 = 39 - 15$$ $$6x = 24$$ 4. **Solve for $x$ by dividing both sides by 6:** $$\frac{\cancel{6}x}{\cancel{6}} = \frac{24}{6}$$ $$x = 4$$ 5. **Final answer:** $x=4$. This means when $x$ is 4, the original equation holds true.