52.33333333.........
mean is (54+66)/2 = 60
The Greatest Common Factor of the three numbers is 6.
36, 42, 48, 54, 60, 66 and so on.
42 48 54 60 66
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66
66 is greater than 54.
It is 54/66 which can be simplified, if required.
They are: 36, 42, 48, 54, 60, 66, 72, 78.
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, . . .
6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, . . .
6 12 18 24 30 36 42 48 54 60 66 72 ............................................
6 12 18 24 30 36 42 48 54 60 66