Final answer:
To calculate the officer's monthly salary, multiply the savings of #12000 by 4, which results in a monthly salary of #48000.
Step-by-step explanation:
If an officer saves #12000 a month, and this amount represents one-quarter of his monthly salary, to find the total monthly salary, we need to multiply the savings by 4.
#12000 (amount saved) × 4 (to represent the full salary) = #48000
Therefore, the officer's total monthly salary is #48000.