Spirit Riding Free: Riding Academy Race by Stacia Deutsch

Friends may fight sometimes, but they always make up . . . right? At Palomino Bluffs Riding Academy, Lucky, Pru and Abigail are learning tonnes of new riding techniques, spending lots of time with their horses and making a bunch of new friends! 
But lately those new friends have been arguing constantly.
   To help, Headmaster Perkins decides to hold a scavenger hunt, promising a mystery grand prize to the team who finishes first. The PALs and their friends are excited to participate until they find out they'll have to team up with the very people they've been fighting against!
   Will the PALs be able to work together with their unlikely teammates?