Aliyah, tammy, and mike are their teacher move books. there are 21 books that need to be carried upstairs. how many books should each student carry if they distribute the work evenly?

If it's only Aliyah, Tammy, and Mike they should each carry 7 books. 

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .