basic ms-dos sim, need help

i am making an ms-dos based simulation based on an ecosystem.

there are three factors, the herbivores (deer), carnivories (bears), and the food supply (the plants). the mathematical model i'm using is quite basic -

a & b - chance of creation

c & d - chance of destruction

s - seconds

(a/b x s) + (-c/d x s) + (a/b x s)

basically, every second, there is a ?/? of something being created and a ?/? of something being destroyed.

i need to create a simulation which will compute this, whilst at the same time displaying on the screen a log file of what is happening. i'm not the greatest with c++, so i need a few pointers on how to do this.

thanks,

JOlszewski