Final answer:
The area of the rectangular porch is 15x² - 26x - 21 in standard form.
Step-by-step explanation:
To find the area of the rectangular porch, we can use the formula A = lw, where A represents the area, l represents the length, and w represents the width.
Given that the length of the porch is represented by (3x - 7) and the width is represented by (5x + 3), we can substitute these expressions into the formula.
So, A = (3x - 7)(5x + 3).
Expanding the expression, we have A = 15x² + 9x - 35x - 21.
Combining like terms, we get A = 15x² - 26x - 21.
Therefore, the area of the porch can be represented as the trinomial 15x² - 26x - 21 in standard form.