97. If the supplemental plan provides that the retirement pension to which the employee would have been entitled under such plan must be based on the salary of the best remunerated years or on the salary of the last years, the pension credit shall be computed on the same basis.
If the number of best remunerated years serving as the basis for computation of the pension under the supplemental plan differs from the number of years used as the basis for computing the pension under this plan, the pension credit accrued by virtue of the supplemental plan shall be adjusted to take account of such difference, in accordance with the regulations made in respect of each supplemental plan concerned.