Redundancy Table To Calculate Lenght Of Service

i am working on a redundancy table to calculate lenght of service at a certain age and what the redundancy in years will be,

age----------------years
less than 23------0.75 per year
23 to 42----------1.5 per year
43 and above----2.25 per year

these figures only count for the years they have been that age

examples

a person who is 22 and worked for two years would get 1.5 years redundancy, 2 x 0.75

a person who is 23 and worked for two years would get 2.25 redundancy 1 x .75 + 1 x 1.5


i can do this table manually adding on to each previous but wondered if someone might have a nice formula that would calculate it automatically

i would imagine there would have to be some kind of lookup to find out how many years they have been in each age bracket