For the calculation of pensions it is necessary to know: years of service, the salary for the position, the salary on a special rank, the percentage bonus for years of service.

The pension is calculated as a percentage of salaries on a post, a special rank and bonus for years of service. Preferential 20 years are 50% of above amount. Each benefit year adds another 3% to the above amount. However, the total pension may not exceed 85% of the above amount.
For clarity, consider an example. Length - 28 grace. The salary for the position is 10 000 rubles, salary for a special rank - 3 000 rubles. Percent allowance for years of service - 70% ( i.e., a factor of 0.7 multiplied by the sum of salaries by position and rank (10000+3000=13000)), we get 0,7*13000=9100 roubles.

Have the sum: 10000+3000+9100=22100 roubles. This is the basic calculated amount. In order to obtain the pension amount, multiply it by the corresponding factor.
As mentioned above, the preferential 20 years are 50% of the base calculation amount (in our case, it - 22100 rubles).

Each benefit year over 20 years gives another 3%. We have 28 years ( that is 8*3=24%). Add 50%(preferential 20 years) and 24% (8 grace). Get 74%.

Thus, the amount of our expected pension is 74% of the base calculation amount (22100 rubles). Multiply 0,74 to 22100 and get 16354 ruble. This is the future pension.