Answer:
x = 4
Explanation:
You want to know the value of x in the arithmetic sequence x, 2x+4, 5x.
Arithmetic sequence
Terms of an arithmetic sequence have a common difference. This means ...
(2x+4) -x = 5x -(2x+4)
x +4 = 3x -4 . . . . . . . . . . simplify
8 = 2x . . . . . . . . add 4-x
4 = x . . . . . . divide by 2
The value of x is 4.
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Additional comment
The common difference is x+4 = 8. The sequence is ...
4, 12, 20, ...