Rory walked 2/4 of a mile more than Louise.
2x 2 is the answer your looking for,
When there are two variables (letters) you combine them by adding
An estimate for the number of ducks would be 62.
There were 30 the first day.
The second day, 8 of those 30 were there as well, so we subtract that from the 40 ducks and get 32.
Add 30 and 32 to get our estimate.
