Question 3
On a particular afternoon, Eugene and Benjamin left their school at the same time and headed towards the bus stop. After running at an average speed of 8m/s for 30 second, Eugene ran past their classmate Dexter. Dexter was walking in the opposite direction the bus stop back to school, as he had left his pencil case in school. 20 seconds later, Benjamin walked past Dexter. Given that Benjamin was walking at an average speed of 1m/s, find Dexter's average speed in m/s.