Mammals account for about 1/10

of all vertebrates. Birds account for about 1/6,
Of all vertebrates. Together, what faction of vertebrates is made up of mammals and birds?

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?