Which of the following is not an axiom of Euclid?

   The axioms of Euclid are as follows:

• Things that are equal to the same thing should be equal to each other.
• When equals are added to equals then, the whole’s are equal.
• When equals are subtracted from equals then, the remainder are equal.
• Things that coincide with one another should be equal to each other.
• The whole is greater than part.
• Things that are double of the same things should be equal to one another.
• Things that are halves of the same things should be equal to one another.

Therefore, 'If equals are added to equals, the wholes are unequal.' is the correct response.