First, this doesn't really belong in "Linear and Abstract Algebra".

I would solve for x: .

Then replace x by that in the second equation:

(You have "+11" but without an "=" there is no equation so I assume you mean "=".)

Now isolate the square root, , and square both sides: .

Again, isolate the square root, and square both sides.

or

.

That is a fourth degree polynomial equaton which might be difficult to solve. The only possible rational roots are the factors of 196 so I would recommend trying those first.