There are lots of ways to solve this system.  But I
can't take the time to do it every possible way.  
What method are you studying?

Elimination, substitution, triangular method, 
Gaussian method using matrices with back substitution,
Complete Gaussian method using row-reduced-echelon
form, AX=B method using inverse matrix, Cramer's rule using
determinants?

I'll give you the answer, which is the same regardless
of the method you are studying:

 

If you are having trouble with the particular method you are
studying, then post again, giving the method you are studying
and we can help you with that particular method.

Edwin