How do I even write an equation for this problem all i need someone to show me how to get an equation so i can solve it.

Question

It is estimated that the Earth is losing 4000 species of plants and animals every year. If S represents the number of species living last year, how many species are on Earth this year?

S-4000.

oh thank you i wasn't sure that's what i was thinking but i was dobting it.

t is estimated that the earth is losing 4000 species of plant and animals every year if s represents the number of species living last year how many species are on eath this year