Answer:
The common difference is d = 14
Step-by-step explanation:
An arithmetic progression should verify that the difference between any two consecutive elements of the progression is always the same number.
Therefore, making first the difference between second and first terms, we have:
8 - (5 - x) = 8 - 5 + x = 3 + x (which should be the actual common difference)
Now the difference between the third and second terms:
2 x - 8 = 2 x - 8
and should be also equal to the common difference we found in our first step:
2 x - 8 = 3 + x
solving for x:
2 x - x = 8 + 3
x = 11
which makes the common difference : 3 + 11 = 14
and the actual sequence: -6, 8, 22
