5. Where the benefits accrued consist in a pension being paid at the date of assessment and where the number of years of service credited during the period of the marriage is less than the total number of years of service credited under the plan, the amount of the pension for the period of the marriage is equal to “A” in the following formula:
C
B x — = A
D
“B” represents the amount of pension paid at the date of assessment;
“C” represents the amount of the contributions and contributory amounts paid during the period of the marriage with interest accrued to the date on which the pension became payable;
“D” represents the amount of the contributions and contributory amounts paid into the plan with interest accrued to the date on which the pension became payable.