The question is asking you to perform a subtraction operation with fractions. You need to subtract the fraction of the candy bar that Josh eats (1/5) from the whole candy bar (which can be represented as 1 or 5/5). To find out how much of the candy bar is left, you would calculate:
1 - 1/5 = 4/5
So, the operation is: \( 1 - \frac{1}{5} \).