Answer: The required simplified fraction is 
 
 
Step-by-step explanation: We are given that in a grocery store there are 4 self-checkout lines and 8 lines with cashiers. 
We are to find the ratio of the number of lines with cashiers to the number of self-checkout lines. 
Let n represents the number of lines with cashier and m represents the number of self-checkout lines.
Then, we have
n = 8  and m = 4.
Therefore, the required ratio of the number of lines with cashiers to the number of self-checkout lines is given by

Thus, the required simplified fraction is 
