Which of the following structural features is associated with arteries but not with veins? A) presence of valves
B) thinner tunica media than veins
C) presence of more elastic fibers and elastic laminae
D) larger lumen than veins

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.

This is what i did 45-5=4040÷4=10so there are 10 white marbles but am not sure is just a question that am not sure