Simplify the expression 5(2x + 3) - 4x.

To simplify the expression 5(2x + 3) - 4x, start by applying the distributive property to the first part of the expression, which involves multiplying 5 by both terms inside the parentheses.

When you distribute 5 to the terms inside the parentheses, you get: 5 * 2x + 5 * 3, which simplifies to 10x + 15.

Now, you combine this result with the second part of the expression, which is -4x: 10x + 15 - 4x.

Next, combine like terms (the terms that are both coefficients of x) by subtracting: 10x - 4x equals 6x. So, you have: 6x + 15.

Thus, the simplified expression is 6x + 15.

Therefore, while the answer provided suggests A (x + 15), the correct simplification leads us to conclude that it should be 6x + 15, which corresponds to a different choice.

Understanding how to apply the distributive property and combine like terms is essential in this process. This will help foster a solid foundation in algebraic manipulation.