Final answer:
The function a(x) = 7 - 6x does not have any critical numbers.
Step-by-step explanation:
To find the critical numbers of the function a(x) = 7 - 6x, we need to find the values of x that make the derivative of the function equal to zero. Taking the derivative of a(x) gives us a'(x) = -6. Setting this equal to zero and solving for x, we get -6 = 0, which has no solution. Therefore, there are no critical numbers for the function a(x) = 7 - 6x.