Answer:
If a, b and c are in arithmetic progression, that means that a + c = 2b. So a + b, a + c and b + c are also in arithmetic progression.
This might help.
X will equal -7 in this problem
Answer:

Step-by-step explanation:
The sum already has common denominators so there is no need to change the denominators. Just add the numerators.


18 times
Since there only two numbers greater than 4 (5 & 6), you subtract 2 from 6.

Then, you divide that from 72.

So, the number of times I would expect the outcome to be greater than 4 is 18.