To solve the equation \( \frac{3m + 5}{4} - \frac{3m}{4} = -2 \), we can start by simplifying the left side.
Combine the fractions on the left:
\[ \frac{3m + 5 - 3m}{4} = -2 \]
This simplifies to:
\[ \frac{5}{4} = -2 \]
Next, we multiply both sides by 4 to eliminate the denominator:
\[ 5 = -8 \]
This is a contradiction, and it indicates that the equation has no solution in real numbers.
Thus, the value for \( m \) that makes the equation true does not exist, or we can say that the solution is not defined. If the equation was set up correctly in the context of needing an actual fraction answer:
Since there is no value for \( m \) that satisfies the equation, the answer could be stated as:
No solution or undefined.
If necessary, please recheck the equation for any possible typographical errors.