I NEED HELP ON NUMBER 6 PLEASE A AND B, ITS

What is the volume of a rectangular prism if the length is 10.4 mm the width is 5 mm in the height is 8 mm

Give all possible names for the line shown.calculation tip: lines can be written with either point first.

Why can't my rank go i have 1723 points, but my rank is only at ambitious, which is only 250 points! like, (p.s. i know this isn't related to math, but i just don't know why it's doing this and i would really appreciate if someone could tell me whats going on with this)