(Easy) Isoline N(t)

Question

I'm sitting with an assignment statistics and functions, and one question in particular has got me perplexed:

An isoline N(t) is given by $$f(x,y)=t.$$ What is N(t)?

I know from previous questions that $$f(x,y)=3000x+2000y$$

Now, how do I find $N(t)$?

Thank you in advance!

Answer 1

It is a contour line...along that line $f(x,y)=constant$. If you change $t$ you get different contour lines, so $3000x+2000y=t$ represents all the contour lines varying $t$.

Answer 2

$N(t)$ is $f(x,y)$. the distribution $n(t)$ is a function of $x$ and $y$. therefore $N(t)=f(x,y)=t$.