Eli had too many fish in his old fish tank. he got a new fish tank and moved 18 fish from the old tank to the new tank. he still had 23 fish in his old tank.

how many fish were in eli's old fish tank at the start?

If the old fish tank has 23 and the new now has 18 then we add these numbers to get 23+18=41

In all honesty, there really is no “work” per say to show. mainly it’s just using the process of elimination. the question is asking which domain(s) would be the most appropriate for the function c(n). n is the number of observed vehicles so right away, 1, 2, and 3 can be eliminated.why? 1, 2 start in the negatives and therefore it is impossible to observe negative cars. so, #4 would be the best answer to the given problem.