a thousand ways you could solve this, but generally need to understand 3 concepts to do so
1. interior angles of triangle add up to 180 degrees
2. law of sines
[tex]\frac{a}{sin A}=\frac{b}{sin B}= \frac{c}{sinC} [/tex]
3. law of cosines
[tex]c^2= a^2+b^2 -2ab* cos(C)[/tex]
my personal suggestion
determine what angle A is, then use law of sines in order to determine side c