Final answer:
The lateral area of a rectangular pyramid requires the dimensions of the triangular faces, specifically their bases and slant heights, which are not provided in the question. Therefore, it's impossible to calculate the lateral area with the given information.
Step-by-step explanation:
To calculate the lateral area of a rectangular pyramid, you need to find the area of the four triangular faces that connect the base to the apex. However, the information given in the question does not completely define the geometry of the pyramid, and thus, we cannot determine the lateral area with the dimensions provided (30 in., 20 in., 20 in.). These numbers could represent the base and height of the pyramid, but without knowing the slant heights or the height of the pyramid itself, the lateral area cannot be computed.
As the problem statement does not contain enough information to complete the task, I cannot provide an accurate calculation for the lateral area of the rectangular pyramid. For a complete pyramid with known dimensions, the lateral area is typically computed by adding up the areas of all the triangular faces, which each can be found using the formula 1/2 × base × slant height of the triangle.