I got an assignment from my math teacher to solve some congruence problems, thing is, I have a really hard time understanding how to solve them . So, help from you guys would be greatly appreciated.

Here are problems:

1.

Prove that 3246(mod 11) = 3246(mod 3) + 3246(mod 5)

2.

Calculate and simplify:

1^3 + 2^3 + ... + 13^2 + 14^2 (mod 7)

Any = should be read as the congruence symbol, don't know how to type that one .