Help!

There are two pan balances, the first pan balance has 2 full juice boxes on the left side and on the right side are 18 grapes along with a half-full juice box. The pan balance is equal.

The second pan balance has an empty juice box on the left side and 6 grapes on the right side. The pan balance is equal.

Now looking at the two pan balances I need to determine the following: A full juice box weighs as much as how many grapes. How much does the contents of one juice box, without the box, weigh in grapes?

I know that what you do to one side of the equation you need to do to the other side. So by removing the 1/2 juice box from the right side of the first balance and also removing a 1/2 juice box from the left side would make 1 1/2 juice boxes equal to 18 grapes.

I need help finding out the possible equations for this problem. I do not just want an answer rather helpful guidance for a better understanding.

Thank you in advance!!(Nod)

Paristnk