[填空题]
A horse canters away from its9tyi ozu(/h rs8-+luco9mrs6 p6*rqm trainer,wq ik h8iyb:,zra+srz- 2e;p in a straight line, moving 150 m away in 24.0 s. It then turns abruptly and gallop:kiwsiarez;-8 +h z,q 2ybr,ps halfway back in 7.5 s. Calculate (a) its average speed $m/s$ and (b) its average velocity $m/s$ for the entire trip, using “away from the trainer” as the positive direction.
