Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 28: 1, 2, 4, 7, 14, 28
Factors of 70: 1, 2, 5, 7, 10, 14, 35, 70
<u><em>The greatest common factor of 42, 28, and 70 is 14.</em></u>
Hope this helps!
And thank you for posting your question at here on brainly, and have a great day.
-Charlie