use the pythagorean theorem to find x, or the missing side, or the hypotenuse (a^2 + b^2 = c^2). Plug in the given values, and get 16^2 + 30^2=c^2 (you can also label it as x^2 instead of c^2). Simplify, and get 256+900=c^2. Simplify and get c^2=1156. Find the square root of that. the final answer is c or x = 34.