PUZZLE 111 Piece of Cake

In the picture, you can see a cake in the shape of the number '6'.
You need to cut the cake in a straight line to make two numbers.
How could you cut the cake to make the largest possible total if you were to add the two numbers together?
What would the total be?

Hint 1

The numbers you will make by cutting the cake are both single digits.

Hint 2

If you turn '6' around, it becomes '9'.

Hint 3

Cut it straight to make two numbers.
Think about how to cut it so that you make a '9'.

Super Hint

Cakes are not flat.
You should be able to cut through it horizontally to make two slices in the shape of the same number.

Answer for 'Piece of Cake'

The answer is '18'.