a) To solve the equation (-5)x = 125, we need to isolate x. We can do this by dividing both sides of the equation by -5:

(-5)x / -5 = 125 / -5

This simplifies to:

x = -25

Therefore, the solution to the equation is x = -25.

b) To solve the equation 40 + (x-38) = 3^3, we need to simplify and isolate x. First, let's simplify the right side of the equation:

3^3 = 3 * 3 * 3 = 27

Now, let's simplify the left side of the equation:

40 + (x-38) = 27

We can remove the parentheses by distributing the -38 to both terms inside:

40 + x - 38 = 27

Combine like terms:

x + 2 = 27

Now, isolate x by subtracting 2 from both sides:

x + 2 - 2 = 27 - 2

This simplifies to:

x = 25

Therefore, the solution to the equation is x = 25.