5
the factors of 20 are 1, 2, 4, 5, 10, 20
the factors of 15 are 1, 3, 5, 15
the common factor of 20 and 15 is 5
Those are a lot of problems. Sorry I can't help you because I can't really see them.
Anthony made three more dollars a month. 84/3 is 28 (Anthony) which is greater than 100/4 (25) (Jeff)
If you combine 2z and -z you get z.