The value of M(8) = 4.
The function M(x) = 7 - 3x is a linear function that represents a constant (7) minus a multiple of a variable (3x).
To evaluate the function at x = 8, you simply substitute 8 for x in the function:
M(8) = 7 - 3(8) = 7 - 24 = 4
So, M(8) = 4.