.
In half an hour, Leona walked 0.5*5 = 2.5 miles.
So, she was 2.5 miles ahead when Sam started his walk.
Each hour the distance between them decreases 6-5 = 1 miles.
So, initial distance of 2.5 miles between them decreases at the rate 1 mile per hour.
Hence, Sam will catch Leona in 2.5 hours after Sam's start.
There are many approaches and many ways of solving such problems.
See the lesson
- Travel and Distance problems for two bodies moving in the same direction (catching up)
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the section "Word problems", the topic "Travel and Distance problems".
Under this topic, I collected a unique set of various types of Travel and Distance problems for those who loves them.
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.