## Assigning prices to variables item1..3
item1 = 15.29
item2 = 1.99
item3 = 18.49

## We can either calculate totals into new variables
shop1 = round(4 * item1 + 16 * item2 + 2 * item3)
shop2 = 4 * item1 + 16 * item2 + 2 * item3
## And print the difference
print shop1 - shop2

## Or calculate the total
total = 4 * item1 + 16 * item2 + 2 * item3 # (this is the same as variable shop2)
## And then print the difference between the total and its rounded value
print round(total) - total

## Or just do it all in one long line
print round(4 * item1 + 16 * item2 + 2 * item3) - (4 * item1 + 16 * item2 + 2 * item3) # this is ugly and prone to errors