Final answer:
To find the number of guests per table, divide 20 guests by the number of tables x, resulting in the expression 20/x.
Step-by-step explanation:
The question posed by the student revolves around finding the appropriate expression for calculating the number of guests seated at each table for a birthday party. If April is inviting 20 guests to her birthday party and plans to seat them at x number of tables, to determine the number of guests seated at each table, one would divide the total number of guests by the number of tables. Therefore, the suitable expression would be the total number of guests 20, divided by the number of tables x, which can be represented as 20/x, corresponding to option D in the original set of multiple-choice answers provided.