We have:

c(k+1) = 1.5 c(k) - e(k)

e(k+1) = 0.21 c(k) + 0.5 e(k).

where k=0 denotes the initial conditions

The percentage increase in k-th year c is:

[c(k)-c(k-1)]/c(k-1) *100 % = [1.5 c(k-1) - e(k-1) - c(k-1)]/c(k-1) *100%

simplifying we get the percentage change in the k-th year is:

50 -e(k-1)*100/c(k-1) %

I'm afraid I don't understand what part b. is asking for.b. If the initial assets are 6000 Euro and the expenses during the first year are 3720 Euro, find the year whose expenses are least as well as the assets at that year's beginning.

RonL