What is this modular arithmetic question asking exactly?

I just completed the first two parts of a question and am not sure how to use my answers in part c).

a) Write down an integer r which is divisible by 2611 and is congruent to 1 modulo 324

b) Write down an insteger s which is divisble by 324 and is congruent to 1 modulo 2611

c) Consider the function given by:

Compute the value of

d)Deduce that is onto.

Is it perhaps notation that I don't understand that is asking me to find an integer x that satisfies both congruence equations?