
We'll represent Louise's, Tammy's, Delores's, and Sheryl's point values with
,
,
, and
respectively since each one is 1 point more than the last.
Add all of these values up and set it all equal to
.

Now, simplify.

Subtract
on both sides.

Divide both sides by
.

Since Louise's score is
, the answer is
.
<h3>Double-checking</h3>
To verify our answer, add the point totals
,
,
, and
.
This equals
, so we can be sure the answer is correct.
5 2/3 divided by 2 2/3 = 17/3 divided by 8/3 = 17/8 = 2 1/8 miles per hour
2 2/3 divided by 5 2/3 = 8/3 divided by 17/3 = 8/17 hours per mile