what is the greatest common factor of 7 and 4?
['The factors of 4 are 4, 2, 1.', 'The factors of 7 are 7, 1.', 'The common factors of 4 and 7 are 1, intersecting the two sets above.', 'In the intersection factors of 4 ∩ factors of 7 the greatest element is 1.', 'Therefore, the greatest common factor of 4 and 7 is 1.']