The height is 10 cm.
Solution:
It says that every two units = 2.5 cm and that the cup is 8 units tall. As a result, you would divide 8 by 2 = 4 in order to only be solving for those 8 units- remember every 2 units, not one = 2.5 cm. After this, you would multiply 4 by 2.5 = 10
You can also add 2.5 per two units using the image.