Final answer:
The equation to represent the number of eggs needed for any number of batches is E = 2B. For 4 batches, Katya needs 8 eggs.
Step-by-step explanation:
The equation that represents the number of eggs Katya needs for any number of batches of cookies is:
E = 2B
where E represents the number of eggs and B represents the number of batches. For every batch of cookies, Katya uses 2 eggs, so the number of eggs needed is directly proportional to the number of batches.
To find out how many eggs are needed for 4 batches:
E = 2 × 4 = 8 eggs
Therefore, Katya will need 8 eggs for 4 batches of cookies.