I've written back for the one i'm having trouble with of the previous in the previous message. Another question is that I want to verify doesn't this problem refer to solving.

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?

Or should I just leave it like you said
S-4000 I'm asking because I'm refering to last part of the question so that means i don't have to solve it am I correct or wrong

I have answered the 6x^2y^3 problem below. I hardly know what to tell you about the earth problem. If you have written the entire problem, then the answer to the number of species of plants and animals on earth today is
S-4000 if there were S on earth last year and 4000 species died out.

Okay I was just unsure because just how i posted the problem that's how its on book. thank you for your help

S=4000