Bill hiked 3/10 mile on the lake trail. then he hiked 5/10 mile on the rock trail to get back where he started how many miles did he hike?

Arace is 10 kilometers long.markers will be placed at the beginning and end of the race course and at each 500 meter mark.how many markers are needed to mark the course for the race?

Can anyone me with this question?

Amotorboat maintained a constant speed of 12 miles per hour relative to the water in going 45 miles upstream and then returning. the total time for the trip was 8.0 hours. use this information to find the speed of the current.