To solve the equation, we first need to plug in the value of M into the second given equation:

M = 3c - 2

2B - 1 + 4c = 3c - 2

We will now solve for B by moving all terms involving B to one side of the equation:

2B - 1 = 3c - 4c - 2
2B - 1 = -1c - 2

Now, we can simplify the equation further:

2B - 1 = -c - 2

Finally, if we divide the entire equation by 2:

B = -0.5c - 1

Therefore, the value of B in the equation is -0.5c - 1.