With the random numbers generated, can I know which RNG seed was used? My teacher challenged us to find out which seed was used to generate some random numbers. I would like to know if it is possible to decipher the seed using the generated numbers (break the linear congruence algorithm). If possible, I ask you to explain how to do it.
If the RNG is cryptographically strong, then you should not be able to do any better than the naive brute force: try each seed until you get matching random numbers.

If this is a homework question, then I would guess that either they used a very small seed (like "3" or "15"), or the RNG is not cryptographic strength and with some time analyzing the linear congruence algorithm, you might see how to invert it.