Each chef at "sushi emperor" prepares 15 regular rolls and 20 vegetarian rolls daily. on tuesday, each customer ate 2 regular rolls & 3 vegetarian rolls. by the end of the day, 4 regular rolls & 1 vegetarian roll remained uneating. how many chefs were on tuesday ? and how many customers were they ?

Let x be the number of chefs at Sushi Emperor and y be the number of customers on Tuesday. The equations that would best represent the scenario above using the number of items uneaten are:
        (regular rolls):       15x - 2y = 4
        (vegetarian rolls):   20x - 3y = 1
The values of x and y from the system of linear equations are:
                            x = 2 and y = 13
Therefore, there were 2 chefs and 13 customers.