Question

Helppppppppppppppppp

Answer 1

Set up a proportion

Units over actual height.
Then solve...for x by cross multiplying

Answer 2

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.